Wessel Wessels

Author Archives: Wessel Wessels

Lifelong weather enthusiast and researcher. Interested in all things weather-related, and how global climate and local weather interact. Owner of multiple home weather stations for almost two decades, but still learning and expanding his knowledge base every day. He is dedicated to sharing his expertise and knowledge to get more people involved and interested in both their local and global weather and how it interacts with climate on a worldwide scale. Love sharing my knowledge on home weather stations, how they work, and the many ways you can use them to your advantage. All in all, he is just a bit of weather nerd.

Virga Rain: Explaining Virga And How It Occurs

Virga-Rain - Explaining What Virga Is And-How It Occurs

You may not have heard of virga before, but the chances are good that you already saw the phenomenon it refers to, more than once. 

This meteorological event is actually a very common occurrence and appears throughout the world wherever precipitation takes place.

If you ever observed a cloud and noticed wispy streaks of rain forming at its base, only to disappear into "thin air," you saw what is commonly known as virga. And your eyes are not deceiving you.

Even a weather radar can clearly identify the presence of rain in a cloud, yet nothing reaches the surfaces. It may seem inexplicable, but there is a very logical explanation for this event.

In this post, we look at what virga is, its characteristics, as well as how it forms. 

Virga Definition

The introduction already provided a clear indication of what virga entails. Before continuing, though, one needs to establish a concise definition of what precisely the phenomenon is. 

What Is Virga?

What Is Virga

Virga is a meteorological phenomenon where precipitation can be observed forming at the base of a rain cloud but disappear before reaching the ground as a result of evaporation or sublimation.

Simply put, virga is precipitation that forms at the base of a cloud but never reach the ground.  Depending on height, the type of precipitation can be solid (snow) or liquid (rain), but usually manifest in the form of rain.

The virga rain is visible as wispy light-colored streaks or tails that extend below the cloud base before disappearing in mid-air.

Virga clouds are also commonly known as jellyfish clouds due to their shape. The puffy structure and dark base of a cumulus type cloud represent the body, while the light streaks of rain below it resemble the tentacles of a jellyfish.

The types of clouds associated with this occurrence are, in general, the type that produces precipitation. They include cumulus, nimbostratus, cumulonimbus, stratocumulus, and altocumulus clouds.

How Virga Occurs

Rain forming at the cloud base level and then suddenly "disappear" in mid-air is quite common, as mentioned in the introduction. The reason you don't see it more often is that it does not always appear in view or at an angle, which makes it more visible.

The rain does not actually disappear. It merely changes from a liquid (rain) into a gas (water vapor) through a process of evaporation or sublimation, making it invisible to the naked eye.

The following steps provide a concise summary of how virga occurs in general:

  1. 1
    Clouds form when moist air cools down to the point of condensation. The resulting microdroplets making up a cloud, are also the source of precipitation.
  2. 2
    The microdroplets crash into each other and combine to form larger droplets of water. When they become too heavy, gravity causes it to fall to the ground as rain.
  3. 3
    In the case of virga, raindrops falling from a cloud usually encounters a layer of warm, dry air. The heat and lack of humidity in the air cause the rain to evaporate or sublimate (turning it back into its gaseous state).
  4. 4
    Evaporation takes place when precipitation changes from its liquid form to gas (raindrops to water vapor). Sublimation takes place when precipitation turns from its solid state directly into a gas (snow to water vapor).
  5. 5
    Virga typically occurs in deserts or other regions with low humidity. It also forms at high altitudes where small ice crystals quickly turn into water vapor as a result of adiabatic compression.
  6. 6
    Evaporation is a cooling process, meaning the virga rain that evaporates leaves a pocket of cold air behind. The cold air can accelerate to the ground at a rapid pace, resulting in a dry downburst, which creates dangerous, unstable weather.
  7. 7
    Unstable weather conditions also occur higher in the atmospheric where virga is the result of adiabatic compression. This heats the air, which causes pockets of warm & cold air at the same altitude, the perfect recipe for turbulent conditions.
  8. 8
    Virga rain is also known as fallstreaks due to its appearance and location beneath the cloud base.

Virga forms in many different ways, but the general steps in which it occurs as well as the characteristics it display, follow the same path as illustrated in the steps above. 


Virga is a common experience, observed almost everywhere precipitation takes place. The rain which drops halfway from the cloud base before disappearing remains a strange sight. This article, however, illustrated how the phenomenon occurs in a perfectly logical way.

The focus of this post was to explain what virga is, how it occurs, and highlight its most essential characteristics.

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


Shelterbelt: Defining A Windbreak And How It Works

Shelterbelt - Defining A Windbreak And How It Works

Wind plays a crucial role in the development of weather occurrences throughout the world. Close to the ground, though, persisting wind activity can have an adverse effect on the surroundings. 

One can see the impact constant wind movement has on the environment through wind erosion occurring in different regions. Along the coast, exposed sand dunes retreat inland due to wind activity, while topsoil is removed from fertile land in increasingly arid territories.

Wind can also have a negative impact on agriculture. It can damage or even destroy entire crops, and also harm livestock that are sensitive to extreme temperatures. 

These are just a few examples where persistent wind activity is not only unwelcome but also damaging with potentially huge implications. Here, relatively simple but very effective human innovation comes into play. It is called a shelterbelt.

Shelterbelts are used throughout the world as an artificial barrier to protect against the harmful effects of wind activity... 

Shelterbelt Definition

Also known as windbreaks, shelterbelts serve a number of different purposes. The main objective always remains the same, though, which is to protect selected areas against potentially damaging wind forces.

Before describing how it works in more detail, one first needs to define what precisely a shelterbelt is:

What Is A Shelterbelt (Windbreak)?

What Is A Shelterbelt

A shelterbelt is a barrier of vegetation, usually consisting of lines of trees and shrubs, created to protect against the damaging effects of wind activity.

It used in agriculture to protect crops and livestock, as well in the environment, to guard against erosion, amongst others.

The main goal and purpose of shelterbelts are to reduce wind velocity dramatically. It accomplishes this task by planting one or more line of vegetation in the path of a prevailing wind to protect a selected area.  

The line of vegetation usually consists of a combination of trees and shrubs to be the most effective. Depending on the specific goal, several lines of vegetation can be planted to provide optimum protection.

The protected area downwind from the windbreak can vary from experiencing very little to no wind, based on the density and number of lines of the protective barrier. The windless region created by a shelterbelt is known as a wind shadow.

How A Shelterbelt Works

As stated in the previous section, a shelterbelt protects a specified area by significantly reducing or eliminating the wind speed over the protected region. The protected area can be a field of crops, livestock, or area of land that is vulnerable to wind erosion.

How A Shelterbelt Works

Illustration showing how a shelterbelt works. Click on image for a larger view.

The illustration above will assist in illustrating how a typical shelterbelt works in practice. Although the figures and measurements will differ from one type of windbreak to another, the fundamental principles remain the same.

The following fundamentals provide a thorough overview of the process through which a shelterbelt functions. 

  1. 1
    A shelterbelt is situated upwind (on the windward side) from the protected area.
  2. 2
    The windbreak is situated perpendicular (at a 90° angle) to the wind direction to provide maximum protection.
  3. 3
    The trees and shrubs used in shelterbelts are semi-permeable, which is crucial. A solid impermeable windbreak causes a sudden disruption of the wind flow. It results in turbulent instead of calm air on the leeward side of the barrier.
  4. 4
    As the moving air reaches the windbreak, pressure builds up on the windward side of the barrier. The majority of air is forced over the top of the shelterbelt. Some escape along the edges while the remaining air filters through the trees and shrubs.
  5. 5
    The wind traveling over the top of the windbreak accelerates to cause a jet of fast-flowing air. It travels aloft for a distance before descending back to the surface.
  6. 6
    The distance the air travels before dropping down is approximately 3-5 times the height of the shelterbelt.
  7. 7
    As a result, a calm area of low-pressure gets created on the leeward side of the windbreak. The length and amount of air movement in this sheltered location depends on the height and density of the shelterbelt.
  8. 8
    After descending back to the ground, the air that traveled over the sheltered region, regains momentum and speed.
  9. 9
    The air pressure at the surface also returns to normal at this point. It acts as a high-pressure buffer to further limit the movement of air within the protected area behind it.

Although differing in size and height, all shelterbelts form and function in the way describes in these steps.

The Purpose Of A Shelterbelt

As mentioned earlier in this post, a shelterbelt is used for a number of different purposes. The most notable application is in the agricultural sector to protect crops and livestock, but also in the environment to protect against wind erosion.

Purpose Of A Shelterbelt

The following list provides a concise summary of the primary applications of shelterbelts used for protecting and shielding different areas:

  • The first and most common use of windbreaks is the creation of barriers on farmland to protect crops. Strong winds will completely destroy young seedlings but are also to break and damage grown plants.
  • In warm weather, prevailing winds can dry out plants and soil, which can stunt their growth and cause permanent damage. In cold weather, the wind chill can lower temperatures to the point where crops can be damaged or even killed.
  • Shelterbelts are also used to protect livestock. Cold conditions caused by windchill cause animals to adjust to temperatures below their thermal neutral zone*, which results in weight loss and also hypothermia, which can be fatal.
  • Windbreaks play a crucial role in the protection of the environment. Placing these barriers in front of exposed land or other areas vulnerable to wind erosion protects and assists in restoring damaged regions.
  • Shelterbelts are also used to control snowdrifts. It is either used to stop snow from entering an unwanted area like a road or homestead or keep snowdrift in place. (The melting water from snow is useful in irrigating pieces of land.)
  • On a farm or other exposed area, a shelterbelt is used as a visual screen. It protects from being seen and potentially become a target of crime, and also mask unsightly objects like roads and buildings from its view. 

(* Thermal neutral zone is the temperature at which an animal experiences optimal health and performance.)


As this post clearly illustrated, shelterbelts or windbreaks are a simple but effective means of protecting against the damaging effect of prevailing winds. They also have a wide range of applications, varying from the practical to the aesthetical.

This article illustrated what a shelterbelt/windbreak is, how it works, as well as highlighted its various uses.

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


Köppen Climate Classification: Defining The Climate Zones Of The World

Köppen Climate Classification

The plant and tree life of any region is a direct result of the prevailing weather it experiences. Similarly, the climate of an expansive terrain is primarily influenced by the underlying vegetation. 

The close correlation between climate and vegetation is evident in every part of the world. (The cold, dry conditions of Antarctica and the moist & humid conditions of the tropical rainforests in South America are just two examples of this powerful interaction.)

The strong connection between the two is also proving to play a key role in categorizing and dividing the global climate into more specific zones. Each climate zone is identified by its unique combination of vegetation, temperature, and precipitation.

These three variables are also determining factors in climate classification. During the late 19th Century, climatologist Wladimir Köppen used vegetation, temperature, and precipitation as the key components in developing the Köppen Climate Classification.

This post describes what the Köppen Climate Classification is, and also looks at the different climate zones it defines.

Köppen Climate Classification Definition

It is already clear that vegetation, temperature, and precipitation are the three main components involved in defining the Köppen Climate Classification.

Before looking in more detail at the different climate regions identified by this system, as well as the role each component play, one needs to obtain a clear and concise definition first of what the Köppen Climate Classification is:    

What Is The Köppen Climate Classification Definition?

What Is The Köppen Climate Classification Definition?

The Köppen Climate Classification is a widely-used classification system that divides the global climate into five climate zones primarily based on vegetation.

Developed by Wladimir Köppen at the end of the 19th century, the system uses precipitation and temperature as the two key components to classify the climate of a region, as they are the determining factors for the type of vegetation that occurs.

The close correlation between climate and vegetation, already mentioned in the introduction, forms the bases for this popular classification system.

Late in the 19th century, climatologist and botanist Wladimir Köppen developed a climate classification system based on vegetation. He used the correlation between vegetation and climate in different regions to divide the world's climate into specific zones.

The resulting Köppen Climate Classification categorizes the global climate into five distinct zones, primarily based on the temperature and precipitation experienced by each one.

Köppen continued to change and refine his classification system, with two of the most important amendments made in 1918 and 1936.

Climatologists continued to make amendments to Köppen's climate classification. Rudolf Geiger was probably the most influential in making important amendments, and the subsequent Köppen-Geiger Classification System is one of the most widely used today.

Climate Zones Of The World

According to the Köppen Climate Classification, the global climate can be divided into five primary zones. These climate zones are based on regional vegetation and defined by the temperature and precipitation that is responsible for its formation.

Koppen-Geiger Climate Map

Köppen-Geiger Climate Map depicting the 5 major climate zones and subcategories

The zones are defined by the capital letters A, B, C, D, and E. The climate zones defined by each letter are:

   A)  Tropical Climates

   B)  Dry Climates

   C)  Temperate Climates

   D)  Continental Climates

   E)  Polar Climates

Each of the five major climate zones covers a vast region and is divided into smaller categories to describe the more specific climate types within each zone.

To best understand each climate type and its characteristics, is to look at it within the primary climate zone in which it falls.

A)  Tropical Climates

Tropical Climate Zone

Tropical (also known as equatorial) climates occur in regions situated around the equator and expand to latitudes of 15° to 25° to the north and south. It can be defined by the following characteristics:

  • It is the warmest of all the climate zones.
  • Regions in this zone have an average monthly temperature of higher than 18° Celsius (64.4° Fahrenheit.) 
  • Annual precipitation exceeds 1 500 millimeters in this zone.
  • High humidity levels and warm temperatures result in a frequent, almost daily occurrences of cumulus or larger cumulonimbus cloud formations.

This zone is divided into three subcategories, which are classified according to temperature and dryness.

  1. 1
    Af - Tropical Rainforest Climate (no dry season.) 
  2. 2
    Am - Tropical Monsoon Climate (short dry season)
  3. 3
    Aw/As - Tropical Savanna Climate (winter dry season)

B)  Dry Climates

Dry Climate Zone

Dry (or arid) climates occur in regions situated at latitudes between 20° to 35° north and south of the equator. It can be defined by the following characteristics:

  • The main feature of this climate zone is the complete absence or extremely low levels of annual precipitation.
  • The very dry atmospheric conditions are the result of the combined evaporation and transpiration levels exceeding the total amount of precipitation.
  • Vegetation is sparse or completely absent as a result of the dry climate with very little precipitation.

This climate zone is divided into desert (BW) and semi-arid (BS) regions, according to vegetation type. It is further categorized into hot (h) and cold (k) zones:

  1. 1
    BWh - Hot Desert Climate
  2. 2
    BWk - Cold Desert Climate
  3. 3
    BSh - Hot Semi-Arid Climate
  4. 4
    BSk - Cold Semi-Arid Climate

C) Temperate Climates

Temperate Climate Zone

Temperate (or mesothermal) climates occur in regions situated at latitudes between 30° to 50° north and south of the equator. It can be defined by the following characteristics:

  • Regions in this climate zone typically experience warm summers with high levels of humidity and mild winter seasons. 
  • During the year, the warmest month is at least 10° Celsius (60° Fahrenheit) or higher, while the coldest month is lower than 18° Celsius (64.4° Fahrenheit) but higher than -3° Celsius (26.6° Fahrenheit).
  • These climate zones are typically located on the edges of continents, along the eastern and western coastlines.

Temperate climate zones are divided into three main categories according to precipitation: mild temperate dry winters (Cw), mild temperate dry summers (Cs), and mild temperate humid (Cf) climates. All three subcategories are further divided according to temperatures:

  1. 1
    Cfa - Humid Subtropical Climate
  2. 2
    Cfb - Temperate Oceanic Climate
  3. 3
    Cfc - Subpolar Oceanic Climate
  4. 4
    Csa - Hot-Summer Mediterranean Climate
  5. 5
    Csb - Warm-summer Mediterranean
  6. 6
    Csc - Cold-summer Mediterranean Climate
  7. 7
    Cwa - Monsoon-Influenced Humid Subtropical Climate
  8. 8
    Cwb - Subtropical Highland Climate
  9. 9
    Cwc - Cold Subtropical Highland Climate

D) Continental Climates

Continental Climate Zone

Continental climates typically occur in regions situated at latitudes between 40° and 75° north and south of the equator. (Although this type of climate is rare in the Southern Hemisphere.) It can be defined by the following characteristics:

  • The average temperature of the warmest month is above 10° Celsius (50° Fahrenheit), while the coldest month is below -3° Celsius (26.6° Fahrenheit).
  • This climate type is usually found in the interior of continents.
  • Regions in this zone experience summers with warm to cool temperatures, while the winters are generally cold.

Continental climate zones are divided into three main categories according to precipitation: continental dry summer (Ds), continental dry winter (Dw), and continental humid (Df) climates. Like temperate climates, they are further divided according to temperature:

  1. 1
    Dfa - Hot-Summer Humid Continental Climate
  2. 2
    Dfb - Warm-Summer Humid Continental Climate 
  3. 3
    Dfc - Subarctic Climate
  4. 4
    Dfd - Extremely Cold Subarctic Climate
  5. 5
    Dsa - Hot Dry-Summer Continental Climate
  6. 6
    Dsb - Warm Dry-Summer Continental Climate
  7. 7
    Dsc -  Subarctic Climate
  8. 8
    Dsd - Very Cold Subarctic Climate
  9. 9
    Dwa - Monsoon-Influence Hot-Summer Humid Continental Climate
  10. 10
    Dwb - Monsoon-Influence Warm-Summer Humid Continental Climate
  11. 11
    Dwc - Monsoon-Influence Subarctic Climate
  12. 12
    Dwd - Monsoon-Influence Extremely Cold Subarctic Climate​​​​​

E) Polar Climates

Polar Climate Zone

Polar climates are located at latitudes above 70° over the Arctic, Greenland, and Antarctica. It is characterized by its all-year-round cold temperatures and little to no vegetation. The following characteristics define it more precisely:

  • The warmest month of the year is below 10° Celsius (50° Fahrenheit).
  • Polar climate regions are extremely dry, with annual precipitation of less than 25 cm (10 inches).

Polar climates are divided into two categories according to vegetation: 

  1. 1
    ET - Tundra
  2. 2
    EF - Ice Cap Climate

Tundra Climates consist of very little vegetation (mainly loose shrubs, mosses, and dwarf trees) over a surface where the soil is frozen for several hundred meters. (A condition known as permafrost.) Ice Cap Climates are completely covered by ice or snow.


As clearly illustrated throughout this article, several smaller climate regions exist within each of the five major climate zones. Vegetation, temperature, and precipitation have been the key factors used in determining each subcategory.

Most countries throughout the world experience multiple sub-climates, and many larger regions are influenced by five or more different climate types at any given time. To explain all the climate zones affecting every country/region, though, will fill an encyclopedia. 

This post provided a broad and thorough overview of the five climate regions as defined by the Köppen Climate Classification. It highlighted the characteristics of each one, as well as laying out their subcategories and how they were defined. 

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


Weather Rockets: A Special Kind Of Sounding Rocket

Weather Rockets - A Special Kind Of Sounding Rocket

Weather stations measure atmospheric conditions near the ground. Weather balloons take measurements in the stratosphere at heights of up to 40 km. But what if readings at greater altitudes are required? 

The vast majority of weather takes place in the lowest layer of the atmosphere, called the troposphere. A number of meteorological instruments measure these conditions, including weather stations, doppler radars, and weather buoys.

Above the troposphere, atmospheric conditions in the stratosphere are still of importance. It is usually measured by weather balloons that can measure a wide array of variables, including temperature, humidity, barometric pressure, and wind speed.

More often than not, the need arises for taking atmospheric readings at even higher altitudes. Weather balloons reach a maximum altitude of only around 40 km (25 miles). They also take almost an hour to reach this height.

This brings us to a special kind of sounding rocket called the weather rocket. These specialized meteorological projectiles literally fill the space between the maximum reach of weather balloons and the lowest orbit of weather satellites.

This post examines what a weather rocket is, its characteristics, as well as how it functions in more detail. It also takes a look at the larger sounding rocket category in which it falls.

Weather Rocket Definition

The introduction provided some clues as to what a weather rocket is, but leaves most questions unanswered. To start understanding this meteorological "device," one needs to address its classification as a type of sounding rocket first.

The best way to summarize the relationship between the two is with the following statement:

"All Weather Rockets Are Sounding Rockets, But Not All Sounding Rockets Are Weather Rockets"

This statement may sound very confusing, but it is actually easy to understand. Sounding rockets are simply a much broader (umbrella) term for a class of smaller projectiles with similar characteristics. Weather rockets fall within this category.

Sounding Rocket Definition

This explanation on its own is not specific enough. As a result, one needs a clear definition of a sounding rocket and its characteristics, before delving into the more specific subcategory of weather rockets:  

What Is A Sounding Rocket?

Sounding Rocket

A sounding rocket is a rocket-powered projectile that carries an instrument array 48 - 805 km (30 - 500 miles) into the atmosphere to conduct scientific testing or take atmospheric measurements.

Sounding rockets usually consist of solid-fueled single-stage rocket motors and a payload that carry an array of instruments (or objects for testing) into the upper atmospheric layers of the earth.

Also known as a research rocket, its primary use is to carry a payload up to an altitude of approximately 45 - 150 km above the planet's surface from where it can conduct dedicated experiments or take atmospheric measurements.

The main advantage of reaching these altitudes is that sounding rockets are capable of accessing the part of the atmosphere between that of high-altitude weather balloons and low-orbit satellites.

(Some advanced sounding rockets are multi-stage rockets that can reach altitudes that far exceed the height at which most satellites orbit the Earth. For example, NASA's Black Brant XII is a four-stage rocket that can reach an altitude of 1 500 kilometers or 932 miles).

The rockets follow a parabolic path with the highest point reached called the apogee. At or near the apogee, the payload/instruments experience a brief period of weightlessness before falling back to earth. It is in this space that most experimenting/testing takes place.

Sounding (or research) rockets are used for several different purposes, from testing instruments and materials that will be used in satellites or other spacecraft, gathering astronomical data, to taking atmospheric measurements.

And it is this last point that brings us to weather rockets.

Weather Rocket Definition

The previous section described the broader category within which weather rockets fall. Although every weather rocket is a type of a sounding rocket, certain characteristics differentiate it from similar projectiles.

Before looking at the features that make them unique, one needs to define what precisely a weather rocket is:

What Is A Weather Rocket?

Weather Rocket

A weather rocket is a specific type of sounding rocket (also known as a rocketsonde) that takes various meteorological readings in the upper atmosphere at altitudes of approximately 75 km (46.6 miles).

Also known as a meteorological rocket or rocketsonde, a weather rocket's primary purpose is to measure atmospheric conditions in the earth's upper atmospheric layers. (Mostly in the mesosphere, but also the thermosphere.)

The radiosonde on a rocket can measure several atmospheric variables, including temperature, humidity, air pressure, and wind speed. It all depends on the specific purpose of each rocket launch, which is not always purely meteorological.

(For example, multiple weather rockets are often used to determine upper atmospheric conditions before a large satellite or manned rocket launch.)

Weather rockets consist of a rocket booster and radiosonde that separates at a set height, from where the payload continues its ascent until reaching the apogee, where it descends with the assistance of a parachute while taking atmospheric measurements.

What makes a weather rocket especially important, is its ability to take weather readings at altitudes of approximately 75 kilometers (46.6 miles). This is well above the range of weather balloons, which reach a maximum height of roughly 40 km (25 miles.)

An increased altitude is just one of several advantage over weather balloons:

  1. 1
    While a weather balloon can take up to an hour to reach the correct altitude, a weather rocket can reach operational heights within a few minutes.
  2. 2
    Surface conditions can contaminate a balloon's radiosonde at its launch, which can interfere with readings at altitude. The enclosure of a weather rocket protects it from outside interference during launch.

How A Weather Rocket Works

The vast majority of weather rockets work on the same principles and operate in the same way. Some of the most well-known rockets ever used for measuring atmospheric conditions is the Loki series of sounding rockets.

By using the Super Loki variant as an example, one will be able to get a clear picture of how most weather rockets function. The following steps describe how a weather rocket operates and the path it follows, from launch until touchdown. 

  1. 1
    The single-stage rocket consists of two sections: The main rocket booster, and the radiosonde payload, situated in the dart/cone section of the projectile.
  2. 2
    After ignition, the rocket launches and accelerates rapidly to approximately Mach 5 (five times the speed of sound.) 
  3. 3
    At a height of 9 144 meters or 30 000 feet, the rocket motor and payload separates. The payload continues its ascent while the rocket motor falls back to the surface. 
  4. 4
    The payload section ascents to its apogee at a height of 76 200 meters or 250 000 feet. (Sounding rockets' apogee varies, depending on payload and rocket output.)
  5. 5
    After reaching maximum altitude, the payload section experiences a brief period of weightlessness before it starts to fall back to the ground.
  6. 6
    As it begins to fall back to the surface, a parachute is deployed to slow down and control the descent. The radiosonde starts to perform the majority of its measurements during this period.
  7. 7
    It takes a weather rocket approximately 2 minutes to reach its maximum height or apogee but can take more than 1.5 hours to return to the surface (with the assistance of a parachute.)
  8. 8
    Upon touchdown, the radiosonde array is retrieved for reuse at a later stage. The total amount of time spend 
Loki Dart Weather Rocket

Although these steps are generally based on the performance and characteristics of the Loki Dart rocket, it is typical of the way in which the majority of weather operates

Key Weather Rocket Facts

This post focused on providing a detailed definition of a weather rocket and the broader category of sounding rockets within which it falls. It also explored its characteristics and took an in-depth look at the steps involved in its operation.

The following list provides a concise summary and highlights the key information about a weather rocket.

  • A weather rocket is a specific type of sounding rocket that takes meteorological measurements in the upper atmosphere at altitudes of roughly 75 km (46.6 miles).
  • Sounding rockets are rocket-powered projectiles that carry instruments to heights of 48 - 805 km (30 - 500 miles) for scientific testing or atmospheric measurements.
  • Meteorological rockets are solid-fueled single-stage rockets that consist of two sections: The rocket motor and the radiosonde payload.
  • After launch, the rocket & payload separate at a set height. While the rocket motor falls back to earth, the instrument payload continues its ascent until reaching its apogee and then start taking measurements with the assistance of a parachute. 
  • Two of the biggest advantages of a weather rocket is the ability to reach greater altitudes than a weather balloon, as well as doing it in a fraction of the time.
  • All weather and sounding rockets follow a parabolic trajectory and experience a brief period weightlessness at their apogee before falling back to Earth.

Although this is not a comprehensive list of all the features and functions of a weather rocket, it highlighted the most important facts. The more detailed information is categorized and laid out throughout the rest of this article.


They may be as well-known as other meteorological equipment, but weather rockets play an essential role in measuring atmospheric conditions at altitudes beyond the capabilities of weather balloons. 

Weather rockets are just one category of sounding rockets. Sounding rockets are used in several different applications, from high-altitude material testing, zero-gravity experiments, to measuring atmospheric conditions before larger manned or satellite launches. 

The article, however, focused on defining a weather rocket, examine its characteristics, and looking at how it functions.

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


Maritime Polar, Continental Tropical, Or Maritime Equatorial… The Types Of Air Masses And Their Characteristics

Types Of Air Masses

If you are confused by the title of this article, don't be. These terms are central to defining and explaining the different air masses that cover the Earth's surface.

At any given time, all regions throughout the world are covered with vast bodies of air. Each one has its specific atmospheric conditions that define the weather in the area it covers. 

Depending on multiple factors, any country can experience more than one air mass. It is not just due to its location, which may lie on the boundary between different air masses, but also as a result of prevailing winds that can move air masses from their position.

This article explores what an air mass is, look at its characteristics, and then provides an in-depth explanation of the different types of air masses.

Air Mass Definition

The climate of any region in the world is largely determined by observing the characteristics of the air mass that occupies it. (Weather can cause short-term atmospheric changes, but the stable air mass determines the prevailing weather conditions of a vast territory.)

Before we examine the major air masses that cover the globe in more detail, one needs first to gain a clear understanding of what precisely an air mass is:

What Is An Air Mass?

What Is An Air Mass

An air mass is a large volume of air with a constant temperature and humidity that covers a vast region. It can vary in size from several hundred to thousands of kilometers.

It remains in position over a region for extended periods and, as a result, takes on the characteristics of the surface it covers (for example, temperature and moisture levels.)

These vast bodies of air that spread out horizontally for up to thousands of miles are separated from one another by weather fronts. It is in and around weather fronts on the boundary between air masses that the majority of meteorological activity takes place.

The characteristics of the kind of weather that occur on the border between air masses depend on the type of weather front present. Weather fronts vary from the more familiar cold and warm fronts to the less familiar stationary and occluded fronts.

(You can learn more about a cold and warm front and their associated weather in this article. You can learn all about a stationary front here, and get in-depth information about an occluded front in this post.)  

The region over which an air mass forms is called a source region. This region can be a land surface or body of water.

Although air masses spread out horizontally over large distances, they can also reach high altitudes with heights of up to 16 km (10 miles), well into the stratosphere.

Types Of Air Masses

A number of classifications systems exist to categorize the major global air masses. Of them, the Bergeron Classification System has been the most widely acknowledged and adopted.

Map Of Global Air Masses

Global Air Masses: Continental Arctic/Antarctic (cA/cAA), Maritime Polar (mP), Continental Polar (cP), Maritime Tropical (mT), Continental Tropical (cT), and Maritime Equatorial (mE) 

According to this system, the classification of air masses first takes place according to the source regions from where they originate. There are four central regions classified according to their latitude:

  1. Arctic/Antarctic Air Mass 
  2. Polar Air Mass
  3. Tropical Air Mass
  4. Equatorial Air Mass

A capitalized initial identifies each of these regions. It means A stands for Arctic/Antarctic, P stands for Polar, T stands for Tropical and E for Equatorial.

But the source region is not the only factor that determines the attributes of an air mass. The amount of moisture in an air mass also plays a significant role in forming its characteristics, which is primarily the result of the type of surface over which it occurs.

Two types of surfaces have the most significant influence on moisture levels:

  1. Continental
  2. Maritime 

Continental surfaces point to landmasses like continents, while maritime surfaces refer to bodies of water. The lowercase initial of each type of surface gets placed in front of the capitalized initial of the source region when identifying a landmass.

For example, "mP" refers to Maritime Polar, while "cT" refers to Continental Tropical.

(A third lowercase letter sometimes gets placed at the end of the first two to create an even more accurate description of an air mass. "k" refers to an air mass that is colder than the surface below, while "w" refers to an air mass warmer than the underlying surface.)

Six primary types of air masses covering the planet emerge when you combine the source region with the kind of surface underlying an air mass.

  1. Continental Arctic (cA) / Continental Antarctic (cAA)
  2. Continental Polar (cP)
  3. Maritime Polar (mP)
  4. Continental Tropical (cT)
  5. Maritime Tropical (mT)
  6. Maritime Equatorial (mE)

The abbreviation for each primary air mass is noted next to the full description. As described, the first lowercase letter indicates the type of surface, while the second uppercase letter represents the source region of the air mass. 

The influence of both the source region and type of surface is evident in the characteristics of any overlying air mass. This will quickly become clear as one takes a closer look at each of the primary air masses: 

Continental Arctic / Continental Antarctic Air Mass

The Continental Arctic (cA) Air mass develops over the ice-covered regions of the North Pole and Greenland. It mainly takes place over the ice and snow covering the area and therefore is classified as continental. 

Continental Arctic

This air mass only takes place during the winter when solar radiation during the day is almost nonexistent. The icy conditions, combined with a lack of moisture, creates very cold and dry atmospheric conditions. 

It's no surprise then that the Arctic Air Mass is colder than other types of air masses.

The Continental Antarctic (cAA) Air Mass develops solely over the continent of Antarctica. Since it only develops over land, it is also classified as continental.

The air is extremely dry and cold as a result of the icy surface and lack of moisture. It is the coldest of all air masses, including the Arctic Air Mass, no matter the time of year or season.

Continental Polar Air Mass

Continental Polar (cP) Air Masses develop over the landmasses of subpolar regions. They primarily affect areas at high latitudes like Canada, the Northern United States, as well as Northern Asia.

It is characterized by cold, dry weather with little cloud cover and precipitation, especially during the winter. The high-pressure system that exists over a region experiencing a Continental Polar Air Mass allows for a very stable body of air.

When it moves south, these air masses start to change as it moves over warmer surfaces and gets subjected to longer and more intense periods of solar radiation. In return, it can provide a pleasant reprieve from warm weather during summer months.

Maritime Polar Air Mass

Maritime Polar (mP) Air Masses form over the freezing North Atlantic and Pacific Oceans near the Arctic. As a result, they are characterized by cold, moist, and unstable weather.

When it originates directly over the water, the air mass can influence adjacent coastlines. For example, the polar air that originates over the North Atlantic has a significant effect on the northeastern part of the United States.

Maritime Polar Air Masses can also start over land and move over a body of water. The continental polar air over Asia moves east over the North Pacific, where it picks up moisture from the surface and develops into a Maritime Polar Air Mass. 

The moisture content in this form of air mass is less than the moisture found in Maritime Tropical Air Masses.

The precipitation associated with Maritime Polar Air is characterized by light but persistent drizzles or rain showers. Depending on the season and severity, it can also produce more moderate showers as well as snowfall.

The air mass impacts the temperatures of the adjacent coastlines differently throughout the year. During the summer, it brings cooler air to the land, while the moderate air mass warms the coastal and border regions during the cold winter months.

Continental Tropical Air Mass

Continental Tropical (cT) Air Masses form approximately 25 degrees north and south of the Equator over the dry, mostly arid regions of the world. It mainly occurs over deserts, including the Sahara, the deserts of Mexico, Australia, and the Arab Peninsula.

Continental Tropical

As a result of the source region and low latitude, Continental Tropical Air Masses are characterized by hot and dry weather conditions. 

Due to the nature of desert weather, temperatures drop as sharply in the evenings as they rise during the day, leading to extreme contrasts in atmospheric conditions.    

Continental Tropical Air Masses are often associated with prolonged dry weather conditions, which can lead to severe droughts in affected regions. Similarly, extreme weather phenomena like heatwaves are also more prone to occur in these atmospheric conditions.

Maritime Tropical Air Mass

As the name suggests, Maritime Tropical (mT) Air Masses mainly occur over the warm oceans of the Tropics and Subtropical Regions. They cover vast areas of the South Atlantic, Indian, and South Pacific Oceans.

With their location near the Equator (with its high levels of incoming solar radiation), combined with the ocean surface, Maritime Tropical Air Masses are characterized by very hot and humid weather conditions.  

They are responsible for a large part of the cloud cover and precipitation in neighboring landmasses. In the United States, a large percentage of the country's rainfall is the result of Maritime Tropical Air. It is also responsible for the majority of the country's thunderstorms.

(It it also the most dominant air mass over the United Kingdom and is responsible for a large percentage of the country's precipitation.) 

Maritime Equatorial Air Mass

Air Masses at or near the Equator primarily form over water, and as a result, are all referred to as Maritime Equatorial Air Masses. (The small portions of land that it covers consist mostly of rainforests and not exposed dry land.)

Maritime Equatorial

Due to the surface and latitude over which they form, these air masses are hot and very humid. The high moisture levels in the air mass are responsible for the large volume of precipitation that occurs over land in the region.

For example, the rainforests of Central Africa and the Amazon in South America receive high volumes of rainfall throughout the year as a result of the Equatorial Air Mass.

Air Mass Key Facts

The following list has been compiled to assist in summarizing and highlighting the essential facts about air masses and their characteristics.

  • An air mass is a large volume of air with a constant temperature & humidity that covers vast regions and remains stationary over an area for prolonged periods.
  • Air masses are separated from one another by a weather front.
  • The area/latitude where an air mass originates from is called the source region.
  • The four source regions where air masses form according to latitude are the Equatorial (E), Tropical (T), Polar (P), and Arctic (A) regions. 
  • Air masses are also classified according to the type of surface underlying it, which can be continental (c) or maritime (m).
  • Continental Arctic (cA) Air Masses are characterized by very cold & dry weather.
  • Continental Polar (cP) Air Masses are characterized by cold & dry weather.
  • Maritime Polar (mP) Air Masses are characterized by cold & moist weather.
  • Continental Tropical (cT) Air Masses are characterized by hot & dry weather.
  • Maritime Tropical (mT) Air Masses are characterized by hot & moist weather.
  • Maritime Equatorial (mE) Air Masses are characterized by hot & very moist air.

Each of these key facts are fully covered and explained in the main article. You can find more information on each topic by simply following the appropriate heading. 


This article clearly illustrated the importance of the world's air masses. They play a crucial role in the formation of the weather and climate patterns that we attribute to different regions and countries throughout the year.

Each air mass is clearly defined and differentiated from one another by the source region from where it originated, as well as the type of underlying surface (land or water). This became evident while describing the characteristics of each of the major air masses.

This post described what an air mass is, how it forms, and also went on to explain the different types of air masses and their attributes in more detail.

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


Ceiling Balloon: What It Is And Its Use In Meteorology

Ceiling Balloon - What It Is And Its Use In Meteorology

No, it is NOT what the name may suggest. If you were imagining a ceiling filled with balloons during a party, you had a balloon ceiling in mind, not a ceiling balloon. Then what is this meteorological device?

As the last sentence eluded to, this type of balloon is used for meteorological observations. Unlike the standard high-altitude weather balloons you may have seen or read about, this type of balloon has a more limited but specific purpose.

It may all sound vague and not very helpful in explaining what it is and what actual purpose it serves in any meteorological service. And this is where this post comes in.

This article clearly explains what a ceiling balloon is, what its characteristics are, as well as how it works in more detail.

Ceiling Balloon Definition

The introduction already provided a broad, but still a vague definition of this meteorological piece of equipment. Before looking at it in more detail, one first needs to gain a clear and concise understanding of precisely what a ceiling balloon is:

What Is A Ceiling Balloon?

What Is A Ceiling Balloon

A ceiling balloon (also known as a pilot balloon) is a small helium-filled balloon used by meteorologists to measure the height of a cloud base or monitor upper atmospheric winds.

These meteorological devices are usually manufactured in red, black, or white colors to increase their visibility, and surveyed from the ground with the assistance of a theodolite.

A ceiling balloon is also known as a pilot balloon or pibal, which may sound more professional and on-point than the "confusing" ceiling balloon description. 

There is, however, a logical reason for the term "ceiling balloon." We know a ceiling balloon measures the height of a cloud base. For all practical purposes, a "cloud base" is also known as the "cloud ceiling" (bar a few small technicalities). Hence the term, "ceiling balloon."

Ceiling balloons should not to be confused with the more familiar and larger weather balloons. The latter can be up to 5 meters (16 feet) in diameter, carry a full array of weather sensors (called a radiosonde), and can reach altitudes of 37 km (23 miles).  

(You can read all about these more conventional weather balloons in this article.)

Pilot balloons (or pibals) are produced in red, black, and white to increase their visibility when tracked from the ground. When fully inflated, the balloon has a diameter of approximately 40 cm (15.7 inches.)

Unlike other meteorological devices, ceiling balloons can only be operated during daylight, since they have to be physically observed from the ground to take accurate measurements.

How A Ceiling Balloon Works

A ceiling balloon works on a simple principle to accurately measure the height of a cloud base (or cloud ceiling) or measure upper atmospheric winds. It makes use of a predetermined rate of ascend and visual tracking to make precise observations.

This process by which it takes place can be explained in a few simple steps:

  1. 1
    The first and most important part of the process is making sure the balloon ascends at the predetermined speed of 140 meters per minute (460 feet per minute). This is done by filling the balloon with helium while being attached to a weighted object.
  2. 2
    The weighted object has a mass calculated to cause it to start lifting once the correct amount of gas has filled the balloon. Once it begins to lift, the balloon will rise at the predetermined ascend rate, and the gas is sealed inside.
  3. 3
    The filled balloon can now be released from a set surface. Once released, the observer will carefully monitor its ascend by visually tracking it while using a timer to calculate the height of a cloud base.
  4. 4
    Once the balloon enters the cloud and disappears from view, the timer is stopped, and the height of the cloud base gets calculated by using the total time of ascent.
  5. 5
    When calculating visibility, the balloon is also observed until it finally disappears from view. In this case, it is also carefully noted when and how far the balloon remains visible after entering a cloud or in misty conditions.
  6. 6
    The balloon's ascent is tracked with the naked eye, or with visual aids like a simple pair of binoculars. In some instances, a more sophisticated device called a theodolite assists in measuring specific angles to help with observing upper atmospheric winds.
Ceiling Balloon Visual Aids

Visual Aids: Theodolite and binoculars

It may seem like a very simplistic and outdated process, but when done correctly, it provides an accurate measurement of a cloud base. It is also able to make a detailed and useful assessment of visibility in misty conditions.

Ceiling Balloon Key Facts

Although most of these were already mentioned throughout this post, the following list has been compiled to highlight the key facts you need to know about a ceiling balloon:

  • A ceiling balloon is a meteorological device used to measure the height of a cloud base or observe upper atmospheric winds. 
  • It is mostly available in red, black, and white colors to increase visibility when tracked from the ground.
  • When fully inflated, a ceiling balloon has a diameter of roughly 40 cm (15.7 inches.)
  • The balloon ascents at a predetermined rate of 140 meters per minute (460 feet per minute) while observed from the ground.
  • When ascending to a height of more than 700 meters without entering the cloud base, it becomes very difficult to keep tracking the balloon, even with the assistance of a pair of binoculars.
  • Ceiling balloons are also used to measure visibility in misty conditions. These measurements are valuable in the aviation industry.
  • The accuracy of using ceiling balloons can be impeded by factors like heavy spells of precipitation that can slow its ascent and result in a false reading.


It may not be the most glamorous or sophisticated meteorological device, but the humble ceiling balloon does what it is meant to do very well. If correctly prepared and inflated, it can provide consistently accurate readings.

It does have some limitations and drawbacks, as mentioned in the previous section, but is still a valuable and easy-to-use tool in the arsenal of any meteorological service.

This article explained what a ceiling balloon is, what its characteristics are, as well as how it works in detail.

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


Acid Rain Facts: What Is Acid Rain And What You Need To Know

Acid Rain Facts - What Is Acid Rain And What You-Need To Know

There area number of pollutants and greenhouse gasses that fill the atmosphere, including carbon dioxide, chlorofluorocarbons, and nitrous oxide. But not all harmful and toxic gases stay in the air...

If the conditions are favorable, a chemical reaction between these harmful gases and natural elements like water moisture in the air, a type of precipitation occurs that is very harmful to both organic and inorganic matter on the surface.

This phenomenon is called acid rain. The term may sound ominous and invoke images of pure acid falling from the sky and eat away at anything it touches. Although the reality is not nearly as horrific, over time, acid rain still causes significant damage to the environment. 

This article examines what acid rain is and how it forms. It then focus on the important facts you need to know about this phenomenon.

Acid Rain Definition

The term "acid rain" sounds pretty self-explanatory. It is not that simple, though, and it is more of an encompassing phrase for types of precipitation with a common characteristic. To establish what precisely acid rain is, the name needs to be more clearly defined.

What Is Acid Rain?

What Is Acid Rain

Acid rain is the umbrella term form any form of precipitation with an unusually high acid level. This phenomenon is the result of sulfur dioxide (SO2) and nitrogen oxides (NOX) emissions in the atmosphere. 

SOand NOX combine with water, chemicals, and oxygen to form the highly corrosive sulfuric and nitric acids that bind with water that falls in the form of acid rain.

Acid rain (also known as acid deposition), describes the different types of acidic elements that get deposited on objects on the planet's surface.   

Although the term may sound to refer to a form of "rain," it implies all types of precipitation that contain an unusually high percentage of acidity. It includes forms of precipitation like rainfall, snow, hail, mist, and snow.

It is important to note that acid deposition does not only occur in liquid form. It can be categorized into two types. The one is quite familiar, while the second takes place almost unnoticed while potentially causing more damage. They are:

1) Wet Depositions

Acid rain in the form of wet depositions is the most familiar kind to observers. It includes any type of wet, acidic precipitation, like rain, snow, mist, and hail.

In regions with a high percentage of rainfall, this is the most common type of acidic deposition, as sulfuric and nitric acid binds with water in the atmosphere before falling to the ground.

2) Dry Depositions

Regions with very or low or no rainfall are not exempt from acidic depositions. In countries like Egypt and other arid countries, acid deposition can occur in the absence of rain.

Here, acidic particles and gases attach directly to surfaces on the ground, including artificial structures, vegetation, and water bodies.

Dry Deposition

For example, the effect of dry acid depositions on the famous pyramids of Giza has become a real and visible concern for archaeological conservationists in the region.  

When rainfall does occur, water can wash the acid away from the surface and carry it to lakes, dams, and other bodies of water, raising their level of acidity, which can severely affect aquatic life.

Depending on the absence of rainfall, dry acid deposition can account for as much as 20 - 60 percent of the total amount of acid deposition in a specific region.

To understand acid rain, one needs to understand acidity. Acidity is measured on the pH scale, which ranges from 0 to 17. The most acidic part of the scale is 0, the most alkaline 14, while 7 is the neutral value where an element is neither acidic or alkaline.

Natural rainwater has a pH level of approximately 5.6 (due to the carbon dioxide present in rainwater that makes it slightly acidic.) Acid rain, however, has a pH level of 4.2 - 4.4 as a result of the presence of sulfuric or nitric acid in rainwater.

Although acid rain can cause longterm damage to the environment and structures, it is not nearly strong enough to cause harm to humans. (For example, vinegar has a pH level of around 2.2, which not only does not harm our skin but can also be safely digested.)

What Causes Acid Rain?

As mentioned in the previous section, rainwater already has a small level of acidity. It is not strong enough to cause any damage to the environment, though. However, when high levels of sulfuric or nitric acid are present in the atmosphere, it can result in acid rain.

Sulfur dioxide & nitrogen oxide do occur naturally. They are produced by volcanic eruptions and weather phenomena like lightning, and can also be the result of biological processes. But natural processes play a very small part in sulfur dioxide & nitrogen oxide production.

The vast majority of sulfur dioxide and nitrogen oxide present in the atmosphere is the result of the burning of fossil fuels (coal, natural gas, and oil) by humans.

Power Station

The burning of coal to produce electricity is the biggest culprit, closely followed by the emissions from automobiles and heavy industries.

These sources release sulfur dioxide (SO2) and nitrogen oxide (NOX) into the atmosphere. Once in the air, SOand NOX react with water, various chemicals, and oxygen to form sulfuric and nitric acid.

Both sulfuric and nitric acid combines with water and fall to the surface in the form of wet deposition, or the corrosive gas can attach directly to objects on the ground in the form of dry deposition in arid regions.

Acid rain does only occur in regions where the toxic acids originated from. Global winds can carry it over vast distances where they result in acid rain on a different continent.

For example, late in the 20th Century, most of the acid deposition in Norway originated in the United Kingdom from where winds carried it over 900 km (560 miles), causing acid rain to destroy the trout and salmon population in Norwegian lakes.

Effects Of Acid Rain

It is clear that acid rain poses a significant threat to the environment. The biggest impact is on objects on the ground that are exposed to acid deposition over an extended period.

A wide range of organic and artificial objects get adversely affected by acid rain. They can be categorized into three sections:

  1. Effect On Bodies Of Water
  2. Damage To Vegetation
  3. Damage To Structures

To get a better understanding of how each category is affected by acid rain, one needs to examine each one in closer detail:

1) Effect On Bodies Of Water

Acid rain has an adverse effect on rivers, dams, and lakes. The most significant impact is on standing bodies of water, especially lakes, where acidity from various sources builds up in the water. 

Bodies Of Water

Acid buildup in lakes is a result of direct precipitation, which is further accelerated by rivers carrying acidic water into the lakes. A further contribution comes from acid on the surface that gets washed away by rainwater and carried to lakes by overland flow.

This acid buildup has a deadly effect on aquatic life forms, including fish, shellfish, and even insects. It already resulted in the complete elimination of some fish species like the brook trout in some lakes.

(Earlier in this post, we already highlighted the deadly effect of acid rain on Norwegian lakes where trout and salmon were almost completely wiped out from some lakes in the region.)

2) Damage To Vegetation

Acid rain has a severe effect on vegetation, especially tree life in regions that experience high levels of acid deposition.

Although plant life and crops can also be affected, it is easier to control acidity in agricultural fields by adding fertilizer to replenish nutrients and also use limestone to counter the acidity in the soil.

Trees are affected by the acid content in rainwater in different ways:

  • They can strip away the protective layers on tree leaves, causing the damaged leaves unable to photosynthesize.
  • Acid rain can also infiltrate the soil around and below a tree, destroying the minerals and nutrients needed for growth.
  • Finally, acid deposition can also release elements such as aluminum that are toxic to trees and other forms of vegetation.

The damage can be so severe that acid rain can result in the large scale dying of trees within a specific region. The Black Triangle on the German border is a region where the forests in the Jizera Mountains experienced widespread tree death due to heavy industrial activity.  

3) Damage To Structures

Buildings, statues, and other artificially created structures are all affected by weathering over time. Acid rain, though, can significantly speed up the breakdown of some structures. Certain natural stone structures are also vulnerable to the effects of acid rain.

Acid Rain Damage To Structures

Some materials are especially vulnerable to acid deposition and can deteriorate at an accelerated pace when subjected to acid rain. These materials include sandstone, limestone, marble, and a variety of metals.

Objects consisting of these materials can suffer severe deterioration or corrosion over time when it is exposed to acid rain. Gravestones and statues are notable examples of objects that can incur extensive damage due to acid deposition.

Acid Rain Facts

The best way to highlight the characteristics and importance of acid rain is to focus on some key facts about this phenomenon, which is also the subject of this article.

Some of the following points were already mentioned earlier in this post, but the following list will serve to highlight the essential facts and add a few new ones to give you a proper overview of what you need to know about acid rain:

  • Acid rain does not pose any short-term danger to humans since the acid content is too diluted and weak to cause any harm.
  • Long-term exposure to high levels of sulfuric & nitric acid in acid deposition can adversely affect people with underlying conditions like asthma, cancer, and cardiovascular diseases.
  • Acid rain can destroy aquatic life in bodies of water, like dams and lakes, by raising acidity levels in the water to make it uninhabitable.
  • Acid deposition can adversely affect vegetation and destroy large sections of trees by depleting essential nutrition from the soil and removing the protective coating from leaves.
  • Artificial structures, specifically those made of materials like limestone, marble, sandstone, and certain metals, are especially prone to damage and deterioration by acid rain.
  • Acid deposition is not limited to regions where sulfur dioxide and nitrogen oxide originated from, but global winds can blow the gases for hundreds of miles to cause acid rain in an entirely different location. 
  • Acidity is measured on the pH scale ranging from 0 to 14, with 0 being the most acidic and 14 the most alkaline. Acid rain has a pH level of between 4.2 en 4.4.
  • Acid rain can only be eliminated by dramatically limiting or halting the production of pollutants like sulfur dioxide and nitrogen oxide.  
  • Acid deposition does not only occur as a result of precipitation. In arid regions with little rain, dry deposition still occurs in the form of acidic gas or dust settling on surface objects.
  • The phenomenon was discovered as early as the 17th Century, and the term "Acid Rain" was coined by Robert Angus Smith in 1872.
  • The gases responsible for the formation of acid rain also occur naturally in the atmosphere and are produced by processes like volcanic eruptions and lightning.
  • The effects of acid rain can be combated. In agriculture, the effects of acid rain on vegetation are neutralized by adding materials like limestone and adding fertilizer to replenish depleted nutrients.
  • Natural rainwater is also slightly acidic, with a pH level of 5.6 (with seven being neutral). It is due to the presence of carbonic acid in the water. This is still too weak to cause any damage to the environment, though.
  • Acid rain has no smell. Unlike strong acids we are familiar, acid rain is too diluted to have any potent smell. It smells no different than natural rainwater.

These are a summary of some of the key facts about acid rain. There is much more information available about this phenomenon, but this article managed to capture the most relevant information and explanations.


Acid rain sounds scary, and although there almost no short-term danger to both the environment and humans, the longterm effect is quite severe and can harm or even destroy parts of the environment.

Since acid deposition takes such a long time to show damage to objects, it was not that easy to provide adequate protection in time, if possible at all. Fortunately, the cause is now known and governments placed regulations in place to limit the production of acidic gases.

The aim of this post was to highlight the key facts of acid rain. To draw a complete picture of the phenomenon, though, it was necessary first to define what acid rain is, how it gets formed, and what its effect on the environment and humans are.

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


Microclimates: What They Are And How They Form

Microclimates - What They Are And How They Form

If you ever entered a forest from an open country road or drove into a big, highly populated city, and suddenly experienced a noticeable change in temperature and humidity, it is not your imagination.

What you experienced is precisely the subject of this article. In another post on this weather site, the difference between local and regional weather was discussed in detail. (You can read more about the difference between the two atmospheric conditions in this article.)

However, even in a local region with its prevailing weather conditions, you can find even smaller areas with their pockets of unique atmospheric conditions. These conditions are known as microclimates.

It is important to note the term "climate" in "microclimate." As discussed in another article on this site, climate refers to the average weather conditions that are unique to an area, compared to weather, which refers to the atmospheric conditions at any given time.

(You can read more about the difference between Weather and Climate in this article.)

As a result, microclimate refers to atmospheric conditions that prevail within a relatively small space for a sustained period compared to the surrounding weather.

It may start to sound a bit confusing, but will become more understandable as we define microclimate and examine its characteristics and how it forms in more detail. And this is precisely what this article will aim to do.

This post examines what a microclimate is and how it forms. It also looks at some of the different types of microclimates.

Microclimate Definition

When meteorologists discuss regional and national weather conditions, it is only natural to get confused between the two. When one throws "microclimate" into the mix, and it is very easy to become completely overwhelmed.

For this very reason alone it is crucial clearly define a microclimate and its characteristics before discussing it in more detail:

What Is A Microclimate?

What Is A Microclimate?

A microclimate is a unique set of atmospheric conditions within a localized area that differs to varying degrees from the greater surrounding region and its weather conditions.

Although this area may be as small as a few square meters, or several hundred square kilometers in size, it is always contained within the overarching weather conditions of its surroundings.

Microclimates do not only vary in size, but also in the amount it deviates from the surrounding atmosphere. You can also find more than one microclimate in a localized area and sometimes in close proximity to each. 

For example, a city with its heat-absorbing streets and buildings, as well as highly reflective materials like glass and metal, creates a microclimate called an Urban Heat Island with temperatures well above its surroundings. 

It is even possible to find a microclimate within a larger microclimate. In a large city, for example, a park or rooftop gardens can create smaller pockets with their own atmospheric conditions. Central Park in New York City is a perfect example of such a microclimate.

These "green zones" within a larger metropolitan area are increasingly used to counter the heat and greenhouse gases created by large cities. The role vegetation plays in the creation of a microclimate will be discussed in more detail in a later section in this post. 

What Causes A Microclimate?

It is clear that a microclimate occurs under a wide range of circumstances. It also takes place in several localized regions throughout the world.

There are numerous factors that cause microclimates to form. However, there are a few common factors that play a significant part in the creation of a pocket of localized atmospheric conditions. They are:

  1. Physical Terrain (Topography)
  2. Bodies Of Water
  3. Man-made (Artificial) Structures  
  4. Vegetation
  5. Soil Composition

Each one of these factors on its own can have a strong enough effect to create a microclimate. However, by combining some of these factors, a more distinct microclimate that contrasts sharply with the surrounding atmosphere can be created. 

The role each factor plays in the creation of localized atmospheric conditions is best understood by looking at each one individually.

1) Physical Terrain (Topography)

The topography of a region is arguably the most important natural contributor to the formation of a microclimate. It is primarily the shape and the change in altitude of a local surface that is responsible for the creation of microclimates.


For example, a mountain or large hill can create two distinctly different localized climates in close proximity. In the Northern Hemisphere, the southern slope of a mountain receives a significant amount more sunlight than the northern slope.

As a result, communities living on the southern slope experience a much warmer and generally drier climate throughout the year. You will also find vegetation that flourishes in warm, dry conditions on the south-facing slope.

In contrast, communities living on the northern slopes experience a cooler and often wetter climate. You will also find vegetation adapted to cool (and in many cases shaded and moist) conditions on north-facing slopes.  

(All the above-mentioned conditions depend on variables like the steepness of the slope, latitude, and the overall humidity of the surrounding atmosphere.)

In the Southern Hemisphere, the opposite happens. North-facing slopes receive most of the sunlight throughout the year, while the southern slopes of a mountain experience more shade and a colder climate. 

It is not only a raised terrain like a mountain that can lead to a microclimate. Valleys and low-lying areas experience a cooler climate compared to surrounding regions due to cold, dense air flowing into these and other natural depressions on the earth's surface.

Many more topographical features influence microclimates, but the examples in this section provide ample evidence of the role topography plays in its creation.

2) Bodies Of Water

Bodies of water have a significant impact on the creation of a microclimate. Since water is able to maintain its temperature much longer than the fluctuations experienced by the surrounding surface, it can create a moderate microclimate within more extreme climates.

For example, in large cities and dense urban areas that have their own artificially created warm microclimate (known as an Urban Heat Island), dams and reservoirs create a much cooler environment within the surrounding urban infrastructure.

Bodies Of Water

On a larger scale, bodies of water have a much more significant effect. When you observe large lakes or dams, you'll notice that they create a moderate climate in and around them very similar to those experienced in coastal regions.

Due to their ability to warm more slowly and maintain their heat for a sustained period, large bodies of water like the Great Lakes, create a moderate climate that results in a cooler environment during the summer months and warmer temperatures during the winter.

This microclimate can spread as far as 48 kilometers (30 miles) inland from the shores of these large bodies of water. As is the case with the Great Lakes, if the size of water bodies are large enough, they can even create their own localized weather system. 

3) Man-made (Artificial) Structures

The subject of large artificial structures like big cities and densely-populated urban regions was already touched on earlier in this article. It is actually one of the most visible examples of a microclimate that contrasts sharply with its surroundings.

The infrastructure of a city creates the perfect conditions for a warm environment. Streets, pavements, and concrete buildings absorb and maintain heat from sunlight for very long periods. Reflective surfaces like metal and glass also create an additional buildup of heat.

As a result, cities have a much warmer microclimate than the surrounding atmosphere, which also lasts throughout the year. This phenomenon is better known as the Urban Heat Island, which you can read about in detail in this article.

4) Vegetation

Vegetation can vary dramatically in scale. It can be the size of your back garden, a park in your city, or the size of a vast forest. (For example, the Black Forest in Germany is 6 009 square kilometers or 2320 square miles.)

It means the scale and impact of this microclimate, depend on the size of the area of land covered by vegetation. Regardless of size, though, the overall effect of any percentage of vegetation remains relatively the same.

One effect of vegetation is called evapotranspiration (evaporation and transpiration) process. This process takes place as a result of soil between vegetation, treetops, and plant leaves, releasing moisture into the air. It has a significant cooling effect on the surroundings.


Another effect of vegetation is the shading provided by larger plants and trees, specifically in a park or forest. If trees are closely spaced together, they create a type of canopy that shades the underlying surface and plants.

The shade allows the soil to remain cold and humid. In return, this cools the air above it, which also moves into its immediate surroundings through wind activity. This cold air, combined with sunlight blocked by the canopies, creates a much cooler microclimate.

The cool microclimate, which vegetation provides (as a result of both evapotranspiration & shading), is increasingly used in cities and dense urban environments to offset the heat created by the Urban Microclimate.

5) Soil Composition

Compared to other factors, soil composition does not seem to play such a significant role in the creation of a microclimate. It does, however, have some impact on climate created on a very localized level. 

Soil's capacity to hold water can have a tangible effect on the immediate surroundings as moisture near the surface helps to promote evaporation, which has a cooling effect.

The composition of a soil determines its ability to absorb and maintain moisture. It consists primarily of sand, clay, silt, and dead organic matter.

Soils like sand with large particles and big pores, allow water to drain through it rapidly without being able to maintain any moisture. Clay, on the other hand, has fine particles with small, if any pores, which result in minimal absorption and more surface runoff.

Soil Composition

Soil with the right amount of sand, clay, and organic matter can absorb and maintain moisture. This not only allows water close to the surface to evaporate and cool the atmosphere but also promotes plant growth, which also has a cooling effect on the air.

Soil's ability to absorb or reflect heat from the incoming solar radiation can also result in the creation of unique localized atmospheric conditions and microclimates.

For example, sand, and other loose, dry types of soil also don't absorb heat but reflects most of the incoming solar radiation. As a result, regions like deserts become very hot during the day, but cools rapidly and becomes very cold during the evening.


It is clear that microclimates appear in various regions throughout the world. They vary in size and can have a significant impact on a localized area and also deviate dramatically from the surrounding atmospheric conditions.

Making use of existing microclimates and introducing new ones within existing local regions can have real benefits. It can battle the adverse effects of artificially-created environments (e.g., parks in a large city) and create new zones to be utilized for activities like agriculture.

This article described what a microclimate is and the different ways in which it gets created. It also highlighted the various factors that are determining factors in the formation of these localized pockets of atmospheric conditions.

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Until next time, keep your eye on the weather!


The Effects Of Ozone Layer Depletion

The Effects Of Ozone Layer Depletion

If you are familiar with the term, "the hole in the ozone layer, chances are pretty good that you grew up in the late 1970s and 1980s, as this was the time where almost everyone knew about this growing danger.

For anyone who was too young or not even born when this event occurred, here's a very short recap of what happened.

Early in the 1970s and 1980s, the scientific community became progressively more worried about the potential harmful effects of ozone-depleting substances (ODS) on the ozone layer. It created a "hole" in the ozone layer above Antarctica that was growing at an alarming rate.

These concerns were formally addressed by the Vienna Convention for the Protection of the Ozone Layer in 1985. In turn, this convention resulted in the signing of a treaty called the Montreal Protocol on Substances that Deplete the Ozone Layer 1987.

20th Anniversary of the Montreal Protocol

Representatives at the 20th Anniversary of the Montreal Protocol in Canada

It was amendments to the Montreal Protocol that resulted in the decision to formally stop the production of CFC's in all developed countries by 1996. 

Subsequent actions lead to the hole in the ozone layer to start shrinking, and reports from NASA in 2019 indicated that it is now the smallest it has ever been.

It is unclear when the damage will be completely repaired, but this is one example of a potentially catastrophic event that was recognized, stopped in time, and even reversed. And all of this due to global recognition and cooperation based on scientific evidence.

You may wonder why this is still such a relevant subject and also continues to receive much attention by meteorological and general scientific communities. There are good reasons for this. The most important being the effects of ozone layer depletion on the planet.

Although this event has been caught in time and reversed, it still needs to be monitored to not let it out of control again. This experience can also serve as a blueprint of how human activities can lead to unintended environmental damage and how they can be addressed.

And this is where this article comes in. The focus of the post will be on the effects of ozone depletion, which will explain why it was addressed with such urgency on a global scale.

To do this, we first need to define what the ozone layer is, as well as its importance to the global environment. The causes of ozone depletion and the hole in the ozone layer will also be examined before we can finally address the potential effects of ozone depletion.

Ozone Layer Definition

Much discussion and debate continued to rage over the ozone layer during the past four decades, with some observers not having a clear idea of what exactly it is. As a result, it is crucial to provide a clear definition first of what precisely the ozone layer is:

What Is The Ozone Layer?

What Is The Ozone Layer?

The ozone layer is a thin blanket of concentrated ozone gas that surrounds the earth at an altitude of approximately 15 - 35 kilometers (9 - 22 miles) in the stratosphere.

It performs the crucial role of absorbing the vast majority (98 percent) of the sun's dangerous ultraviolet light.

Ozone gets created in the stratosphere. As high levels of UV radiation hit an oxygen molecule (O2), it creates a freed oxygen atom. The oxygen atom then combines with an oxygen molecule (O2) to form ozone (O3.)

Ozone also forms primarily over the tropics. High altitude winds then carry the ozone rich air towards the polar regions.

The ozone layer do not just vary in height but also in thickness. It varies throughout the year, but in general is thinner over the equator and thicker over the polar regions.

Importance Of The Ozone Layer

The ozone layer is an extremely thin layer located in the stratosphere. At its highest concentration levels, it is also still only ten parts per million of ozone. Despite its low density, the ozone layer plays an indispensable role in protecting all life on the planet.

It absorbs the vast majority (roughly 98 percent) of all ultraviolet radiation from the sun. (The dangers of this type of radiation will be addressed shortly in the "Effects Of Ozone Layer Depletion" section.)

Ozone (O3) consists of three oxygen atoms and is a relatively unstable molecule. And it is this instability that helps to protect us.

It may sound confusing, but it is both the destruction and reformation of ozone in the stratosphere that protects the earth from UV light. It can be explained as follows.

Solar Radiation

An abundance of oxygen molecules is present in the stratosphere. When ultraviolet light from the sun hits one of these molecules, they cause it to break up into two separate oxygen atoms.

A single oxygen atom (O1) is very unstable and quickly finds an oxygen molecule (O2) to bind with, which results in the formation of an ozone molecule (O3). And it is this molecule that protects the earth from UV radiation.

In summary: Oxygen Atom (O1) + Oxygen Molecule (O2) = Ozone (O3)

Importantly, when UV light hits an ozone molecule, it absorbs the radiation and converts it into heat instead of allowing it to pass through.

During this process, though, an oxygen atom gets stripped away again, leaving an oxygen molecule (O2) and a single oxygen atom (O1).

In summary: Ozone (O3& UV Exposure → Oxygen Atom (O1+ Oxygen Molecule (O2) 

The simultaneous creation and destruction of ozone is a natural process but creates a fine balance where the amount of ozone produced is equal to the amount of ozone destroyed. 

This process is also known as the Leaky Bucket Theory. If you compare the ozone layer to a bucket with a hole in it, the bucket will remain full as long as the amount of ozone leaking out (being destroyed) remains the same as the amount of ozone added (newly created.)

It is precisely for this reason that ozone-depletion substances, which caused more ozone to be destroyed than can be newly created, resulted in a huge imbalance and the resulting depletion of the ozone layer.

In turn, increasing amounts of dangerous ultraviolet radiation were able to reach the planet's surface. Fortunately, the Montreal Protocol addressed the alarming rate of depletion, and the ozone layer is recovering.

But this is all evidence of just how delicate this balance is and how vital it is to be maintained to allow the ozone layer to continue protecting against UV radiation.

Causes Of Ozone Layer Depletion

There are a number of substances in the atmosphere that causes ozone breakdown or depletion. They are known as ozone-depleting substances (ODS), which can occur naturally or have an artificial origin.

Hydroxyl (OH·) and nitric oxide radicals (NO·) are both occurring naturally in the atmosphere and are highly reactive, meaning they are short-lived but can easily react with another substance. In the stratosphere, this results in the interaction and breakdown of ozone.

The biggest cause of ozone depletion, though, are the man-made chemicals that were released into the atmosphere during the late 20th Century. Of these chemicals, chlorine and bromine are by far the biggest threats.

These substances are created by chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and other gases that were used as coolants in commercial appliances like refrigerators and air-conditioners.

Ozone Depletion Diagram

Diagram illustrating how ozone-depleting substances are destroying ozone

Once chlorofluorocarbons and hydrochlorofluorocarbons reach the stratosphere, they get exposed to ultraviolet radiation, which breaks them down into chlorine or bromine. It is in this pure form of these substances that is able to destroy ozone on a large scale.

These chemicals are able to break down ozone by stripping away an ozone atom. Chlorine, for example, destroys ozone by reacting with and breaking the ozone molecule apart to form chlorine monoxide and oxygen. 

The simple equation looks as follows: Cl + O3 = ClO + O2

It is both the capacity and lifespan of chlorine and bromine that make them so destructive. For example, one chlorine atom is able to destroy 100 000 ozone molecules. Bromine is up to 40 times more damaging than chlorine, but there is much less of it in the atmosphere.

Chlorine can also remain in the stratosphere for up to 100 years and bromine for up to approximately 65 years. These long lifespans allow these ozone-depleting substances to remain and continue to disrupt ozone levels for a sustained period. 

Effects Of Ozone Layer Depletion

The delicate balance between the creation and destruction of ozone is crucial. The depletion of ozone in the stratosphere during the late 20th Century as a result of zone-depleting substances resulted in severe disruption of this balance.

The large-scale destruction of ozone by ozone-depleting substances in the stratosphere during the last Century resulted in more of the gas being destroyed than new ones created.

This imbalance led to an alarming decline in the amount of ozone in the stratosphere, with weaknesses known as "holes in the ozone layer" appearing over regions like Antarctica.

The amount of ultraviolet radiation that will be allowed through if the zone layer is compromised will have devastating and deadly consequences to all life on the planet.

Ultraviolet light can be divided into three types of radiation:

  1. UV-A Radiation 
  2. UV-B Radiation
  3. UV-C Radiation

Of these three, UV-C radiation is by far the most dangerous. It can cause severe skin burns in a short time, lead to skin cancer, and also cause permanent eye damage, which includes conditions like cataracts. Fortunately, the ozone layer blocks 100 percent of all UV-C light. 

UV-B radiation is less dangerous, but can still cause skin burns, and is associated with certain types of skin cancers like carcinoma. Again, the ozone layer is able to block approximately 90 percent of all UV-B radiation.

UV-A radiation is the only type of UV light that penetrates to the surface without interruption from the ozone layer. It was considered a harmless form of radiation, but recent studies reveal long-term exposure could lead to premature skin aging and cancers like Melanoma.

The point of this breakdown of ultraviolet radiation and the potential impact of its different components on human beings is to highlight just how devastating the effect of ozone depletion will be.

Effects Of Ozone Layer Depletion

Just to put this in context, an article published in National Geographic in April 2019, stated that without the Montreal Protocol, "the U.S. would have seen an additional 280 million cases of skin cancer, 1.5 million skin cancer deaths, and 45 million cataracts—and the world would be at least 25 percent hotter."

And the impact on the rest of our environment wasn't even focused on in this section. For example, ultraviolet radiation (especially UV-B light) can also damage plants on a cellular level, alter their DNA, and can even lead to plant death. 

It is also important to note that animal life is also impacted in very much the same way as human life by the effects of ultraviolet radiation. Even freshwater and marine life do not escape the effects of UV light.

In summary, it is safe to state that all life on earth will be adversely affected by ozone depletion and the resulting increased ultraviolet radiation.


Throughout this article, especially during the last few sections, the importance of the ozone layer was highlighted, as well as how crucial it is for the delicate balance that keeps the ozone in place and protects against the vast majority of UV radiation, to be maintained.

It is important to note that, although the majority of damage done to the ozone layer by ozone-depleting substances has been stopped and even reversed, the ozone layer remains fragile and is only estimated to be fully restored by approximately 2050.

The ozone layer also remains under constant attack from existing and new threats, with new forms of chemicals released into the atmosphere, as well as global warming and climate change evolving, which may all have longterm effects on ozone that has yet to determined. 

The focus of this article was to explain what the ozone layer is and just how crucial it is for the protection of all life on the planet. It also highlighted the different causes of ozone depletion and the effect it can have on the environment and human, animal, and plant life.

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


Mother Of Pearl Clouds: Explaining The Appearance Of Nacreous Clouds

Mother Of Pearl Clouds - Explaining The Appearance Of Nacreous Clouds

As one publication stated, "once seen are never forgotten." I am referring to a rare, unique, as well as breathtaking phenomenon that occasionally occurs in the skies above the Arctic Regions.

This phenomenon is called mother of pearl clouds, a sporadic cloud formation that appears in regions within and bordering the Arctic Circle. These clouds are more commonly known as nacreous clouds.

What makes nacreous clouds so unique is not only their rare occurrence but also the wide array of colors they display that has a uniquely surreal look to them. It is from their unique color pattern that the name "mother of pearl clouds" originated.

(The reason for the "mother of pearl" association and resulting name will be explained in more detail later in this article.)

For the remainder of this article, the name "nacreous clouds" will be used to describe this phenomenon. Wherever necessary, though, the term "mother of pearl clouds" will be brought into the discussion to explain the association or draw a correlation.

In this article, we will focus on what nacreous clouds are, how they form, and what their characteristics are.

Nacreous Clouds Definition

From the introduction alone, it has become crystal clear that a nacreous cloud occurrence is a very unique and awe-inspiring phenomenon. It begs the question as to what they are and how they form.

Before looking at their origin and formation, one first needs to establish a clear and concise definition of what nacreous clouds are:

What are Nacreous Clouds?

What Are Nacreous Clouds

Nacreous clouds are polar stratospheric clouds that occur high in the stratosphere moments after sunset in regions close to or in the Arctic Circle.

They are recognized by their unique display of iridescent colors and patterns. They are also known for their rare appearances, which are also mostly limited to polar regions.

Nacreous clouds are high-level clouds that occur in the stratosphere over polar regions at heights of 15 000 – 25 000 meters (49 000 – 82 000 ft). They are officially known as polar stratospheric clouds.

This phenomenon can be best observed within the first two hours after sunset when rays of light illuminate the clouds from below the horizon. The resulting iridescent colors produced are a product of ice crystals scattering and refracting the light as it reaches the cloud.

Iridescence is an optical occurrence that causes objects to display vivid rainbow-like colors. In the case of nacreous clouds, the colors can vary from luminous and vivid, to the familiar pastel colors that are so unique and contributes to the surreal effect of this phenomenon.

Why Are They Called Mother Of Pearl Clouds?

The word "nacreous" in nacreous clouds is derived from the word "nacre." Nacre is the substance responsible for the iridescent rainbow and pastel colors known as "mother of pearl" found in certain mollusk shells.

In jewelry, a pearl starts forming in a mollusk shell as nacre starts building up around a small particle like a grain of sand. As the pearl grows, the inside of the shell also gets covered with nacre.

The unique iridescent colors of the inner shell covered with this substance closely resemble nacreous clouds. Hence the subsequent naming of the meteorological phenomenon as "mother of pearl clouds."

This section gave a clear explanation of what nacreous clouds are, their characteristics, and why they display their unique "mother of pearl" colors. The focus should now shift to how these cloud phenomena form, which we will address in the next section.

How Nacreous Clouds Form

As previously stated in the definition, nacreous clouds form at high altitudes, approximately 15 000 – 25 000 meters (49 000 – 82 000 ft) above the surface in the lower stratosphere. It is these high altitudes that allow them to remain illuminated for some period after sunset.

The clouds also need to be illuminated from below for iridescence to occur, which means mother of pearl clouds can only be observed after sunset when the sun is between 1 - 6 degrees below the horizon.

Mother Of Pearl Clouds

Nacreous clouds also form under very low temperatures. The clouds can only form once the air temperature drops below -78° Celsius. It is also part reason why the phenomenon is mostly observed in Arctic regions, which experience these low temperatures.

The air over the polar regions is normally very dry, making cloud formation a very rare occurrence. When clouds do form at high altitudes above the surface, the ice crystals in nacreous clouds are much smaller than those that form in normal cloud formations.

It is these smaller ice crystals that allow the sunlight to be scattered and refracted in such a way to produce the vibrant iridescent colors that are so unique to this occurrence.  

During the day, nacreous clouds may resemble pale Cirrus clouds that may be almost unnoticeable. Once the sun dips below the horizon, however, the clouds start to display bright luminous colors.

As the sun continues to sinks further below the horizon, the bright luminous clouds slowly change into a mixture of pink, green, and mostly pastel-colored formations, which contributes to the the surreal effect that is so unique to nacreous clouds.

Unlike most other fast-moving cloud formations that occur much lower in the atmosphere, the aptly named mother of pearl clouds also seems to remain stationary in the sky as a result of their great height.


Nacreous (or mother of pearl) clouds are rare occurrences that appear almost exclusively over the Arctic regions and are seen by very few people in selected areas as a result.

Yet, their appearance and surreal color displays are so unique and captivating that they are better known than there rarity suggests, especially in meteorological circles.

This article examined and explained what nacreous clouds are, their characteristics, and how they are formed. It also described why they are called mother of pearl clouds and described the shared connection between the two phenomena.  

Never miss out again when another interesting and helpful article is released and stay updated, while also receiving helpful tips & information by simply  following this link .

Until next time, keep your eye on the weather!


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