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.

Does The Moon Affect The Weather? How Earth’s Only Satellite Is Influencing Our Atmosphere Conditions

Does The Moon Affect The Weather

Sitting approximately 380 000 km (236 000 miles) away from Earth, it's hard to imagine that the moon can have any influence on the planet's climate and weather.

One can easily assume that a "piece of rock" this far away from Earth, and a quarter of its size will have very little if any influence on the planet's atmospheric conditions. But you know what they say about assumptions...

In short, the moon does impact the planet's weather, but not in the way you may think.

This article explains how and why the moon impacts the weather and examines the mechanisms involved in the process.

Does The Moon Affect The Weather?

Clearly, a much broader explanation is needed to fully understand exactly how the moon impacts the planet's atmospheric conditions. But first, we need a more concise and precise answer to the primary question this post is addressing.

Does The Moon Affect The Weather?

How The Moon Affects The Weather

The moon does affect the weather, but indirectly. Through its gravitational force, it mainly has a direct effect on the ocean's tidal activity, which impacts the flow of the ocean currents in return.

And it is the flow of cold and warm ocean currents that largely determines weather conditions in most parts of the world.

From this cryptic description, it is evident that the moon's gravity, its tidal activity, and the ocean currents are the key components involved in the manipulation of weather activity in the atmosphere. The upcoming section will lay out exactly how this process takes place.

The primary way in which the moon affects the weather is through the indirect manipulation of ocean currents. The type of weather introduced to a new region, as a result, will largely depend on the properties of the ocean water present in the affected current.

(Warm water will favor cloud formation and is almost synonymous with tropical Cyclone development. Cold water, on the other hand, is more conducive to the creation of dry weather conditions.)

A second notable effect of the moon on atmospheric conditions is its impact on polar temperatures. Measurements taken by satellite showed that temperatures at the Poles are higher during Full Moon than New Moon.

On average, temperatures during Full Moon are 0.55° Celsius (0.99° Fahrenheit) higher than New Moon. These temperatures may seem small and insignificant, but even at this scale, it still has a significant effect on weather.

A less significant effect of the moon is its ability to increase air pressure at the edge of a tidal bulge, as the increased water height causes the air to compress slightly. In this case, the increase in atmospheric pressure is not large enough to have any impact on the weather.

How The Moon Affects The Weather

This section describes how the moon affects the weather on our planet. To understand the steps involved in this process, one needs to clarify two of the key components:

  1. Gravity  
  2. Ocean Tides

As already stated, gravity is one of the primary factors allowing the moon to influence weather and climate. In fact, it is ONLY the moon's gravitational force that enables it to have any impact on the Earth's atmospheric conditions.

As a result, it is essential to understand how gravity works and how it allows the moon and other celestial bodies with mass to exert force on different objects.

1) Gravitational Force Of The Moon On Earth

Gravity is the strength with which the planets and other large celestial bodies attract objects to their centers. All objects with mass also have gravity. And it is the large mass of the moon that enables it to display the strong gravitational force that even influences objects on Earth.

Gravitational Force Of The Moon On Earth

Diagram showing the impact of the moon on Earth's oceans, showing the tidal bulge that forms during High Tide.

The moon's gravity primarily influences the ocean tides on the planet's surface, which impacts the ocean currents and the weather in return.

(The moon's gravity influences all bodies of water, even the fluid in a cup of tea. The only reason the latter is not visible is that it occurs on such a small scale that it is visibly unnoticeable.)

And this brings us to the subject of ocean tides, the big disruptor that impacts ocean currents and helps to shape the weather:

2) How The Ocean Tides Affect The Weather

Tidal activity refers to the rise and fall (height) of water levels in a body of water like the ocean. The part of the sea directly underneath the moon's location experiences the largest "pull," causing water levels to expand vertically and rise. This rise is called a tidal bulge.

As the moon orbits the Earth, the tidal bulge follows it along the surface of the ocean. This horizontal movement is responsible for the creation of tides. And it is the creation of tides near the coast that largely impacts the flow and direction of ocean currents.

As previously mentioned, ocean currents are one of the primary drivers of weather activity. Their flow is mainly determined by three factors:

  1. Tidal Activity
  2. Wind Movement
  3. Thermohaline Circulation (A change in water density as a result of temperature and salinity.)

Ocean currents that are formed by tidal activity are known as tidal currents. Depending on the characteristics of the water present, these currents can result in rainy weather (in the presence of warm ocean water) or dry weather (mostly as a result of cold water).

Full Moon

During full moon, the moon's gravity is at its strongest, resulting in Spring Tide, where water levels are at its highest and sea levels at the coast rise more than at any other point. During this period, atmospheric readings are now also able to clearly show an increase in rainfall.

The moon does not influence the weather directly, but the thorough explanation in this segment of the different objects and occurrences involved makes it easier to understand. 

The complete process through which the moon impacts the weather on Earth can be summarized in the following steps:

  1. 1
    All objects have gravity, which increases with mass. The large mass of the moon allows it to exert more gravitational force on Earth than any other celestial body.
  2. 2
    The part of the ocean directly below the moon's position above the planet experience the biggest gravitational pull.
  3. 3
    Similar to a magnet attracting another metal object, the moon pulls at the surface of the ocean, causing it to expand vertically and increase in height. 
  4. 4
    This vertical expansion is known as a tidal bulge, which sweeps across the ocean's surface as it follows the moon orbit around the Earth.
  5. 5
    The tidal bulge is responsible for creating new and manipulating/redirecting existing ocean currents. Ocean currents affected by tides are called tidal currents.
  6. 6
    Ocean currents are one of the main driving forces of weather. As a result, the influence of tidal activity on these currents leads to the creation of new weather patterns, which depend on the characteristics of the water the currents carry.

In summary, this section explained how the moon affects the weather indirectly through gravity, which leads to the creation of ocean tides. In turn, tidal activity drives & shapes the ocean currents that are largely responsible for the formation of specific weather conditions. 


As this article clearly illustrated, the moon does affect the weather, but not directly. Through gravity, it is responsible for the creation of tides in the ocean directly below. In return, the tides influence ocean currents, which directly drive weather activity around the world.

The moon's impact on atmospheric conditions can seem insignificant. It does, however, have a big enough and noteworthy influence not to be ignored when gathering meteorological data or making a weather prediction. 

The primary aim of this post was to describe the effect of the moon on the Earth's weather, how it occurs, and also look at the different factors and processes involved. 

Feel free to leave me any comments, questions or suggestions, and I will get back to you as soon as possible.

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Until next time, keep your eye on the weather!


Arcus Clouds: What They Are And How They Form

Arcus Clouds - What They Are And How They Form

Clouds literally come in all shapes and sizes, but there is something unique about the appearance of arcus clouds. And they have more meaning than simply putting on a spectacular display.

Under the right conditions, many cloud formations make for some of the most striking photographs you can take. Some clouds, though, are so visually impressive and awe-inspiring that a picture doesn't do it justice. Arcus clouds are one such example.

This article focus on what arcus clouds are, how they form, as well as the different types of arcus clouds.

Arcus Cloud Definition

It is clear that arcus cloud formations are responsible for some of the most spectacular views one can observe from the planet's surface. But there is more substance to this meteorological phenomenon than merely looks.

What Is An Arcus Cloud?

what is an arcus cloud

"Arcus Cloud" is the umbrella term used for low-lying clouds that spreads out horizontally, usually from the boundary of a larger storm system like a thunderstorm.

These visually striking cloud formations usually appear in the form of shelf clouds or roll clouds.

The summary provides a concise but cryptic definition of what an arcus cloud is and how it forms. A broader definition is needed to fully understand this type of cloud formation.

Arcus clouds are low-altitude clouds with the cloud base forming at the height of approximately 2 kilometers (6500 feet).

Arcus clouds are divided into two main categories: Shelf Clouds and Roll Clouds. As a result, arcus clouds are either wedge-shaped or in the shape of a horizontal tube-shaped column (depending on whether a shelf or roll cloud develops).

The two major types of clouds associated with the formation of arcus clouds are Cumulus and Cumulonimbus. Notably, the severe updrafts and downdrafts present in cumulonimbus clouds are responsible for the creation of many spectacular arcus formations.

Unlike the cumulonimbus clouds that form the basis for the formation of many arcus clouds, arcus clouds themselves develop and spread out in a horizontal fashion.

Arcus clouds pose no direct danger in the form of precipitation or strong winds, but in many cases, act as a precursor for approaching thunderstorms and severe weather.

How Do Arcus Clouds Form?

Although the two types of arcus clouds, shelf and roll clouds, have unique characteristics and a specific way in which each one develops, they both have a similar origin.

Arcus Cloud Formation

Cold air flow out from the storm front and spreads horizontally, forcing the warmer air at the surface into the air. The arcus cloud forms along this border of rising warm air and advancing cold air.

The principle way in which arcus clouds form can be summarized in the following steps:

  1. 1
    Thunderstorms are characterized by strong updrafts and downdrafts in the stormcloud. It is the strong downdrafts present at the leading edge of a thundercloud that is primarily responsible for the creation of arcus clouds.
  2. 2
    Cold air, cooled down by altitude and precipitation, is carried to the ground by downdrafts from where it spreads out horizontally in front of the storm system. 
  3. 3
    The heavier cool air spreads out quickly over the ground and pushes underneath the warmer moist air, lifting it into the atmosphere.
  4. 4
    As the warm air rises and cools down, condensation takes place, which leads to the formation of arcus clouds with their unique shape & characteristics.
  5. 5
    Depending on the specific atmospheric conditions and location, this process leads to the formation of the familiar wedge-shaped shelf clouds, or the round cylindrical-shaped roll clouds.

Both shelf clouds and roll clouds each have a unique appearance with characteristics of their own, which we will address in the following section. 

Types Of Arcus Clouds

As stated in the summary, arcus clouds can be divided into two primary types of formations: 

  • Shelf Clouds
  • Roll Clouds.

These two types of arcus clouds may have a similar origin, but appear substantially different with different characteristics which can be best understood by looking at each cloud formation individually. 

Shelf Cloud: The Best-Known Arcus Cloud Formation

The most common type of arcus cloud is the ominous-looking shelf cloud that usually precedes large thunderstorms. When discussing arcus clouds, this is the type of cloud formation that generally springs to mind. 

What Is A Shelf Cloud?

what is a shelf cloud

A shelf cloud is a type of arcus cloud that is characterized by its wedge shape and horizontal development, which usually forms at low altitudes at the leading edge of storm clouds.

Shelf clouds usually develop out of the parent cloud called a cumulus congestus cloud. Congestus clouds are cumulus clouds which are taller than they are wide, in other words, with strong vertical development. They are also often a precursor to cumulonimbus clouds.

The familiar ragged-looking underside of a shelf cloud is a result of turbulent winds, as well as wind shear caused between the updrafts and downdrafts.

Arcus clouds in the shape of shelf clouds are synonymous with a derecho, a widespread and potentially devastating storm system you can read all about in this article

Shelf clouds appear at the leading edge of this dangerous storm front, and although they pose no danger themselves, their appearance point to the looming threat of the derecho that follows close in its footsteps.

As a shelf cloud passes overhead, it is usually followed by a dark tumultuous section of sky, commonly known as the whale's mouth in meteorological circles. This stretch of weather slots in between the appearance of shelf clouds and the arrival of the thunderstorm.

(The dark, turbulent stretch between the edge of a shelf cloud and a thunderstorm is sometimes characterized by a distinct wavy appearance, known as asperitas clouds. These clouds don't appear that often but are almost as spectacular as the shelf cloud itself.)

Shelf Cloud Formation

The formation of a shelf cloud is identical to the process described earlier in this post. From the fifth point, though, the process is unique to the development of shelf clouds:

As the cold air from the outflow boundary (leading edge of the storm) moves forward, it tilts the rising warm air along its boundary.

It is along this boundary between the warm updrafts and cold downdrafts that shelf clouds form. As the warm air keeps rising along this border, it cools down, and condensation takes place, which results in the formation of a shelf cloud.

Roll Cloud: Shelf Clouds' Less Famous Cousin

A lesser-known type of arcus formation is called a rolling cloud. It is the second of the two types of arcus clouds.

Although a roll cloud is classified as an arcus cloud, it differs significantly from its more famous cousin, the shelf cloud. One needs to take a closer look to understand its unique characteristics, but one first needs to define it more clearly: 

What Is A Roll Cloud?

what is a roll cloud

A roll cloud is a rare type of arcus cloud that is characterized by its round tube-shaped formation, which forms at very low altitudes and appears to rotate on its horizontal axis.

It acts as a single wave known as a soliton and, unlike a shelf cloud, develop completely independent from other clouds.

As already stated, the appearance of roll clouds is a rare occurrence. It is no less spectacular than well-documented cloud systems but is a relatively rare occurrence. The biggest reason for their scarcity, is that the weather conditions has to be close to perfect for them to occur.

In the WMO's Cloud Atlas, it is now officially called volutus clouds. Although it is still viewed as a type of arcus cloud, the World Meteorological Organization (WMO) recently classified it as an entirely separate cloud species.

What makes a roll cloud unique is that it appears as a solitary independent cloud, completely detached from any parent cloud. On very rare occasions, one can view several roll clouds appearing in succession.

Roll clouds also act like a soliton when it comes to its motion. A soliton is a single wave with a single crest that moves ahead without changing its speed or size. (Which sums up the movement of a roll cloud.)

It is evident that roll clouds have some characteristics that clearly distinguish it from shelf clouds, even though it still falls within the same family of clouds. 

Difference Between A Shelf Cloud And Roll Cloud

The biggest difference between a shelf cloud and a roll cloud is the fact that a shelf cloud forms part of the larger storm cloud from which leading-edge it develops, while a roll cloud is an entirely independent cloud, detached from any cloud formation.

The well-known Morning Glory Cloud formation is arguably the best example of a roll cloud formation. It is the only type of roll cloud that can be predicted with any amount of certainty, and occur mainly in Northern Australia and The Gulf OF Carpentaria.

Roll Cloud Formation

Although the formation of a roll cloud generally forms in the same way as the process described earlier in this post, it also differs in a significant way: 

A roll cloud forms completely independent from any bigger cloud system. In many cases, it occurs without any other significant cloud development even in sight. 

Although not physically attached to a parent cloud, a roll cloud still forms at the leading edge or gust front of a storm system.

In some instances, the downdrafts that accompany a storm system forms some distance in front of the stormcloud's edge. As a result, a roll cloud can form at the border between updrafts and downdrafts, without the presence of the larger storm cloud formation.

Sometimes, though, a thunderstorm will clear up and dissipate completely, leaving only the updrafts and downdrafts behind. In turn, they can lead to the formation of roll clouds in otherwise clear and fair weather.


It is clear that all arcus clouds follow a similar pattern when it comes to their development and factors involved in the process. The physical manifestation of the two types of arcus clouds, however, are dramatically different.

Shelf clouds develop their familiar ragged wedge-shaped form, while roll clouds are characterized by their round, tube-shaped formation. Shelf clouds further develop at the leading edge of a storm cloud, while roll clouds form independently from any other cloud.

In conclusion, this article focused on explaining what an arcus cloud is, how it develops, and highlighting the different types of arcus clouds. 

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!


The Fogbow: Rainbow’s Less Glamorous Cousin

Fogbow: Rainbow's Less Glamorous Cousin

Whenever you see a fogbow, you will be forgiven for thinking you are observing a form of rainbow. Though you won't be completely wrong, fogbows are the result of a different meteorological occurrence.

Although they are both the result of the same meteorological process, a fogbow appears during foggy/misty conditions while a rainbow occurs in the presence of a rain shower (as the names suggest).

It may not seem like much of a difference, but the characteristics of fog results in a ghostly white phenomenon not too dissimilar from a rainbow stripped of all its color.

This article examines what a fogbow is, look at its characteristics, as well as how it occurs. 

Fogbow Definition

As the introduction already eluded to, in the simplest terms, a fogbow appears as a completely desaturated rainbow with its predominantly white appearance. 

Before delving deeper into why and how it occurs, one first needs a clear and precise definition of what a fogbow is.

What Is A Fogbow?

What Is A Fogbow

A fogbow is a predominantly white semicircular bow that appears in the presence of fog when sunlight is reflected by water droplets within the fog bank.

Unlike the luminous spectral colors of a rainbow, a fogbow appears primarily white as a result of the way in which the microdroplets in fog reflects sunlight.

This summary provides a concise explanation of a fogbow, but to better understand why it occurs and how it differs from its more glamorous cousin, the rainbow, a broader clarification is needed. 

Although the name "fogbow" is the most commonly known and widely used name for this phenomenon, a few other terms are also synonymous with this occurrence:

  1. White Rainbow (Aptly named after its predominantly white appearance.) 
  2. Circle Of Ulloa (Named after General Antonio de Ulloa, who first draw attention to the phenomenon in the 18th century.)
  3. Ulloa's Ring (Another variation of the name used in the previous point.)
  4. Ghost Rainbow (Named after the ghostly white appearance of a fogbow.)

A fogbow is a relatively rare sight compared to rainbows, and do not occur that often. What makes them even harder to spot, is the fact that they can appear almost indistinguishable from the surrounding fog with only a hint of contrast that makes visible.

white rainbow

Since a fogbow appears at the antisolar point, the sun needs to be approximately 20 degrees or less above the horizon for it to be visible as a semicircular ring. Any higher and the phenomenon will theoretically fall below the horizon and disappear from view. 

(An antisolar point is a position on the celestial sphere situated directly opposite the sun from the observer's point of view.)

The semicircular ring visible above the horizon is only part of a full circle, which can be viewed in its totality if the observer is situated at an elevated position like a mountaintop.

Fogbows are almost as big as rainbows, but the ring (or bow) is much broader in size due to the amount of diffusion and light scattering by the small size of the droplets present in fog.

The following section will detail the process through which a fogbow occurs. 

How A Fogbow Occurs

Like a rainbow, a fogbow is observed with your back towards the sun while looking directly into a bank of fog in front of you.

  1. 1
    The microdroplets in fog diffract (bend) and break up the sunlight into its constituent spectral colors, which results in the familiar color pattern that is so unique to a rainbow.
  2. 2
    However, as the microdroplets in fog are a fraction of the size of raindrops (up to a hundred times smaller), they react and scatter sunlight differently than rainbows.
  3. 3
    The size of the droplets results in the formation of multiple smaller beams of spectral light reflected and scattered in all directions. Many of these smaller beams of lights come together, overlap, or merge to display a combined color of white.
  4. 4
    This process explains why a fogbow appears as a predominantly white ghostly semicircle. (Sometimes displaying spectral colors on the extreme side of the spectrum with a shade of red on its outer edge and blue on its inner edge.)

Fogbows Are All About Diffraction

The formation of a fogbow is also impossible to take place without the occurrence of a process known as diffraction.

spectral colors

As white light passes through a raindrop (as illustrated by the prism), refraction causes it to be broken up into its constituent spectral colors.

Diffraction is defined as the bending of light as it travels around or through an object. The diffraction of light as it passes through a raindrop is responsible for the breaking up of light into its spectral colors. We view these diffracted colors whenever observing a rainbow or fogbow.

The larger waterdrops in rain acts as a prism and break up (diffract) the sunlight into its constituent spectral colors, which is clearly visible in the resulting luminous rainbow.

Unlike rain, however, the smaller-sized droplets in fog cause less diffraction (bending) of light, which means a smaller separation into constituent spectral colors. 

This means the light viewed by the observer is seen as primarily white (the combination of all spectral colors).

The conditions and specific characteristics of any fogbow may vary from one occurrence to another. However, the process described here, as well as the requirements that need to be in place for the phenomenon to occur, always remains the same.


As this post clearly highlighted, the process that is responsible for the formation of a rainbow is identical to the one that creates a fogbow. The only real difference is the size of the droplets in a fog bank.

The size of these micro-droplets, though, completely changes the characteristics of a fogbow, displaying a semicircular ring stripped of all its color. It is unique and eyecatching in its own right and can produce a spectacular display under the right conditions.

This article explained what a fogbow is, described its characteristics, and went on to explain its formation 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!


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!


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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!