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.

What Phase Is The Moon In During A Solar Eclipse? Examining The Difference Between A Solar And Lunar Eclipse

The Difference Between A Solar And Lunar Eclipse

The phenomena known as a solar and lunar eclipse are arguably one of the most anticipated and well-known celestial events. Every year in different locations worldwide, people experience this visual display. 

Observations of these almost "supernatural" events date back thousands of years and have been documented as early as 1137 BC in Chinese literature. (A book from the Zhou Dynasty called Zhou-Shu described what is believed to be a lunar eclipse.)

Through the centuries, many cultures and religions attached a large amount of symbolism and importance to these phenomena. Their significance is so widespread across different civilizations through the ages that it justifies a large separate post, but is still worth noting.

The question in the heading of this article "What Phase Is The Moon In During A Solar Eclipse"  is just one of many frequently-asked questions raised when it comes to a solar or lunar eclipse.

It also illustrates just how involved both the moon and sun are in the occurrence of a solar as well as a lunar eclipse.

And this is what this article will focus on: Explain what a solar eclipse is, what a lunar eclipse is, and how they differ from each other. It will also describe how each process takes place and also look at the effect they have on the weather.

Solar Eclipse and Lunar Eclipse Definition

Before we answer the question posed in this article's title, or even start to examine how a solar and lunar eclipse occurs, we need to establish a clear definition of each event.

Solar Eclipse Definition

Of the two events, a solar eclipse is arguably the most dramatic and spectacular, with the effect of day turning into night within a couple of minutes, only to return to daylight a few minutes later. Not to mention the spectacle of viewing the sun during this event.

(Needless to say, special care should be taken when looking at the sun during a solar eclipse, including special glasses or a dark piece of film.)

Although most of us already experienced a total or partial solar eclipse at some point, it is crucial to understand what exactly this phenomenon is before we can begin to describe how this event occurs:

What Is A Solar Eclipse?

What Is A Solar Eclipse

A solar eclipse occurs when the moon's path crosses between the earth and the sun, causing it to cast a shadow on a specific part of the earth's surface.

From a vantage point on earth that falls within this shadow, the sun can be seen as partially or totally blocked out by the moon, resulting in the light turning from dusk to darkness.

The most spectacular type of solar eclipse is called a total solar eclipse, which occurs when the moon completely blocks out the sun. This form of solar eclipse occurs very rarely.

A total solar eclipse can be viewed from some viewpoint on the planet appropriately every 18 months. However, it estimated that the time it would take for a total solar eclipse to occur at the exact same location will be roughly between 360 and 410 years.

It is rare since the sun, moon, and earth must be in complete alignment, and the moon must be at the right distance between the sun and earth to completely block out the sun.  

The process through which a solar eclipse occurs will be explained in more detail in an upcoming section within this post.

Lunar Eclipse Definition

It may not be as spectacular as a solar eclipse or have such an impact on atmospheric conditions back on earth. However, a lunar eclipse remains a rare and special event that can be visually just as captivating under the right conditions.

Before examining exactly how this event occurs, one needs to establish a clear definition of a lunar eclipse to completely understand this phenomenon first: 

What Is A Lunar Eclipse?

What Is A Lunar Eclipse

A lunar eclipse occurs when the earth's path crosses between the sun and the moon, causing the shadow of the earth to block the sunlight reaching the moon.

Depending on its position, the planet's shadow can result in a partial or total eclipse of the moon.

Like a solar eclipse, the most impressive and visually captivating form of lunar eclipse is a total lunar eclipse. It occurs very seldom, though, approximately once every 2.5 years.

Like a solar eclipse, a total lunar eclipse is only possible when the sun, moon, and earth is incomplete or nearly perfect alignment. Partial lunar eclipses, however, are a much more common occurrence.

Unlike a solar eclipse which can only be viewed from specific a location on the planet's surface that falls within the moon shadow, it is possible to observe a lunar eclipse from almost anywhere on earth.

With the basic definition of each phenomenon covered, attention can turn to the different processes through which a solar and lunar eclipse occur.

How A Solar And Lunar Eclipse Occur

From the description of both a solar and lunar eclipse, it is clear that they have a lot in common. Both involve the sun, earth, and moon. The three celestial bodies also need to be near perfect alignment for each phenomenon to occur.

But there are also are distinct differences between the two events, which we will look examine more closely by looking at each process separately.    

How Does A Solar Eclipse Occur?

As the moon orbits the earth, the earth rotates on its axis, and both orbits the sun, one can start to understand why a solar eclipse does not occur that often.

Add to this equation the fact that the moon orbits the earth at a different angle and speed than the earth rotates and revolves around the sun and it's surprising that a solar eclipse is possible to take place at all.

But as most of you know, it does happen. A total solar eclipse can be viewed from some location on the planet appropriately every 18 months, as already mentioned.

How A Solar Eclipse Occurs

The Process Through Which A Total Solar Eclipse Occur. Click On Image For A Larger View.

During this period the moon passes between the sun and the earth. As it crosses between the two, its casts a shadow on the earth's surface.

Since the earth rotates, this shadow travels across the planet's surface, creating what is called the path of totality.

A total solar eclipse can only be seen by anyone that is within the path of totality. If you are not located within this path but still relatively closely, you will be able to observe a partial solar eclipse.

All solar eclipses only last for a few minutes, with some exceptions where the total length of an eclipse can exceed seven, although this is very rare.

At this point we come to the question asked in the title of this article:

What Phase Is The Moon In During A Solar Eclipse?

A solar eclipse can only occur during New Moon (when the entire moon is covered in darkness and not visible from the earth's surface.) 

A total solar eclipse can be seen within the moon's dark inner shadow (called the umbra.) A partial solar eclipse can be observed within the earth's lighter outer shadow (called the penumbra).

Types Of Solar Eclipses

Depending on the alignment and distance of the moon between the sun and earth, different forms of solar eclipses can occur. There are four primary types of solar eclipses:

1) Partial Solar Eclipse:

A partial solar eclipse occurs when only a certain percentage of the sun gets eclipsed by the moon. It mostly occurs under one of two different circumstances.

The first type of partial eclipse occurs when the position from where the event is observed, falls outside the path of totality.

It means that any observer outside the moon's umbra (dark inner shadow) will only be able to view a part of the sun to be eclipsed.

The second type of partial eclipse occurs when the earth, moon, and sun is not completely aligned. It causes the moon's shadow to miss the surface of the planet.

As a result, the only type of solar eclipse that can be observed in these conditions will be a partial one. 

2) Annular Eclipse

Annular Solar Eclipse

An annular solar eclipse occurs when the diameter of the moon appears smaller than the diameter of the sun and is unable to block it out completely, leaving the outer surface of the sun exposed.

As a result, the sun's outer surface appears like a bright ring in the sky. This form of solar eclipse takes place when the moon is at its furthest point from the earth in its orbital path.

3) Hybrid Solar Eclipse

Also known as an annular-total eclipse, this eclipse occurs when the phenomenon shifts from an annular to a total solar eclipse and vice versa during a single event as it travels along the path of totality on the surface of the planet.

Like a total solar eclipse, this form of eclipse is also only possible when the earth, moon, and sun are in perfect alignment. It is also the rarest of all eclipses and makes up only 5 percent of all solar eclipses combined.  

4) Total Solar Eclipse

The most well-known of all eclipses is the total solar eclipse. It occurs when the earth, moon, and sun are in complete alignment, and the moon covers the whole surface of the sun, with just the sun's bright corona (the sun's atmosphere) visible.

In able for observers to view a total solar eclipse, they need to be in the path of totality, described earlier in this post. 

How Does A Lunar Eclipse Occur?

The same orbit of the moon around the earth, and both celestial bodies' rotation around the sun that results in a solar eclipse, is also responsible for a lunar eclipse.

In able for a lunar eclipse to occur, the moon must be in its Full Moon Phase (with the whole surface of the moon illuminated.)

The sun, moon, and earth must also be in perfect or near-perfect alignment to allow a lunar eclipse to take place. (The same conditions required for a solar eclipse to occur.)

How A Lunar Eclipse Occurs

The Process Through Which A Total Lunar Eclipse Occur. Click On Image For A Larger View.

In the case of a lunar eclipse, however, the earth passes between the sun and moon, casting its shadow over the moon's surface.

Unlike a solar eclipse, which can only be observed from a specific location on earth, as already stated, a lunar eclipse can be viewed from almost any region on the planet.

Depending on the exact positioning of the earth, different forms of lunar eclipses can occur. They can be categorized into three primary types of eclipses:

1) Penumbral Lunar Eclipse:

This type of eclipse occurs when the earth's penumbra (light outer shadow) is cast over the moon, causing a slight darkening of the moon surface, which is sometimes invisible to the naked eye.

2) Partial Lunar Eclipse:

The form of eclipse where a specific portion of the moon falls within the earth's umbra (dark inner shadow). It creates the effect of a particular sized "bite being taken out of the moon."

3) Central Lunar Eclipse:

The type of eclipse most of us are familiar with where the sun, earth, and moon are perfectly aligned, causing the earth's shadow to block out any light from the sun completely.

The only light that the moon receives during a total lunar eclipse is the faint light refracted from the surface of earth. 

As a large amount of blue light is scattered while travelling through the atmosphere, it gives the moon a reddish tint. The phenomenon better known as the "Blood Moon" is the result of this process.

Difference Between A Solar And Lunar Eclipse

Throughout this article, we already briefly touched on the majority of differences between a solar and lunar eclipse. The following list was created to provide a summary of the primary differences between the two events:

  • A solar eclipse occurs when the moon travels between the earth and the sun, while solar eclipse occurs when the earth's path crosses between the moon and sun.
  • A solar eclipse is only visible from a specific location on earth at any given time, while a lunar eclipse can be observed from almost any point on the planet's surface.
  • For a solar eclipse to occur, a New Moon must be present, while a lunar eclipse occurs during a Full Moon.
  • A lunar eclipse does not affect the weather, while a solar eclipse has a small and temporary, but noticeable effect.
  • A solar eclipse is observed during the day, while a lunar eclipse is best viewed at night.
  • A lunar eclipse occurs more frequently than a solar eclipse.
  • Special care should be taken when viewing a solar eclipse to avoid damage to the eyes, while a lunar eclipse can be safely viewed with the naked eye.
  • A solar eclipse has a much more significant effect on human activity since it causes a sudden onset of darkness during the middle of the day while a lunar eclipse gets observed during the night when it is already dark.

There are other subtle differences between the two events, but the ones listed here are the primary differences between a solar and lunar eclipse.

Effects Of A Solar & Lunar Eclipse On The Weather

Although both phenomena look impressive and significant, they can create the impression that they may have a considerable impact on the earth's atmospheric conditions. This impression is only partially correct.

The moon is already most notable during the evening when the sky is covered in darkness. A lunar eclipse will only result in the darkening of what is already a small light source, so it has little if any effect on our weather.

A solar eclipse, on the other hand, is an entirely different matter. It occurs during the day when the sun is the primary source of light, heat, and other forms of solar radiation that the earth needs to support life on the planet.

Solar Eclipse Darkening

A solar eclipse occurs over minutes where the earth is quickly covered in darkness, rather than the several hours it takes the sun to near the horizon in the afternoon before setting. As a result, there is a slight but relatively quick drop in temperature during this event.

(According to NASA, temperatures can drop 10 - 15° Fahrenheit during a solar eclipse.)

Solar eclipses also have an impact on wind speed and direction. Wind is simply air flowing from an area of high pressure to an area of low pressure. (You can read all about wind and how it is created in this article.)

A low-pressure system near the ground is created as the sun warm the surface, which warms the air above it in turn. As a result, the warm air starts to rise, leaving air with a lower pressure behind. Wind blows from surrounding high-pressure areas to this location.

During a solar eclipse, the heating of the ground surface slows down, and the low-pressure system is much weaker, resulting in the wind blowing from high-pressure regions to have a much slower speed.  

Even though a solar eclipse has some effect on local atmospheric conditions, it is relatively mild and mostly temporary. It is, therefore, safe to state that solar and lunar eclipses have minimal and only temporary effects on the weather.


There is no doubt that a solar and lunar eclipse are both events that capture the public's imagination. A total solar & lunar eclipse are as spectacular as they are rare.

These two occurrences have a lot in common, but as this article illustrated, they also differ in a variety of ways. In a sense, they are two sides of the same coin. 

This article explained what a solar and lunar eclipse are, and how they occur. It also illustrated how these events differ from each other and how they may affect the weather.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


Accurate Forecasting: Benefits Of Owning A Home Weather Station

Accurate - Forecasting Benefits Of Owning A Home Weather Station

An increased number of people already own a home weather station. Some even own more than one of these devices. It raises the question as to what the real benefits are and if you should get one yourself.    

In today's world, where instant information is available for just about everything that goes on in and around you, it is no wonder that people will want to have instant access to their weather data as well.

And this growing trend is not limited to just weather enthusiasts. Worldwide, individuals want the convenience of knowing what the weather is like inside and outside their homes to dress accordingly and make the necessary preparations.

An increasing amount of large and small companies operating outdoors are also starting to rely on the information personal weather stations provide to monitor conditions and schedule projects.

All of which may still leave you in doubt whether you will get any real benefit out of owning your own weather station. This post defines a home weather station and then looks at its various benefits and advantages.

Home Weather Station Definition

There are literally hundreds of weather stations available today. They range from a simple analog thermometer to highly integrated electronic weather stations with multiple indoor and outdoor sensors, while also connected to the internet and your smart home.

Before we start to discuss it in detail and look at all the benefits, it is essential to first gain a clear understanding of precisely a home weather station is:

What Is A Home Weather Station?

What Is A Home Weather Station

​A home weather station is a meteorological device designed to measure and display one or more atmospheric conditions through a number of different weather sensors (both indoor and outdoor).

More advanced weather systems use the collected data to calculate and make short-term weather predictions.

The advantage of the wide range of home weather stations available, is that you can locate a device that serves your specific needs.

There is a weather station out there that will suit you perfectly. No matter if you just need to know what the temperature inside your home is, or you want to measure every possible atmospheric condition in & outside the home, make forecasts and log all your weather data.

Through the years, home weather stations advanced to the point where they can measure almost every possible weather element. The following is a list of weather elements that the advanced Ambient Weather WS-2902A Osprey weather station can measure:

  • Temperature (Indoor And Outdoor) 
  • Relative Humidity (Indoor And Outdoor)
  • Dew Point Temperature
  • Barometric Pressure
  • Rainfall
  • Wind Speed 
  • Wind Direction 
  • Ultraviolet Radiation
  • Solar Radiation

Needless to say, you don't need half these functions to enjoy all the benefits a home weather stations can provide, but it does give you an indication of just how advanced modern meteorological instruments became.

Benefits Of Owning A Home Weather Station

And this brings us to the main focus of this post. In order to illustrate the different benefits of home weather stations, we will use two examples which are used for two different purposes.

The first is the Ambient Weather WS-2902A Osprey. This is the station I use for all my "serious" weather observations and research. It is one of the most advanced home weather stations available and sits on the more expensive side of the weather station price scale. 

La Crosse Technologies 308-1414b Weather Station

The second is the La Crosse Technology 308-1414B. I use this affordable device in my study to get a quick indication of the basic weather conditions in and outside the home. It is very affordable for what it offers, but note that there are even more affordable devices available.

These two stations will be used to illustrated specific benefits and drawbacks throughout the following sections. The most significant benefits of home weather stations can be summarized seven key points:

  1. Real-Time Weather Monitoring
  2. Accurate Forecasting (For Your Location)
  3. Global Integration And Sharing Of Data
  4. Ease Of Use
  5. Convenience And Comfort
  6. Remote Access
  7. Affordability

You will be able to get a quick understanding of what each key point entails by simply glancing at the concise explanation provided as we go through each point in more detail.

1) Real Time Weather Monitoring

A weather forecast is exactly that; A forecast. It does not tell you what the current atmospheric conditions are but predicts what the future state of the weather will be. And it definitely not tell you what the present weather conditions are like in your specific location.

This is where the first and most obvious advantage of a home weather station comes into play. Even the most modest and affordable device will tell you what the basic atmospheric conditions are like at any given time in your immediate surroundings.

(And even if a local weather forecaster or app shows you the indicated real-time data, it is not specific to your exact location and an educated guess at best.)

2) Accurate Forecasting (For Your Location)

National and regional forecasts do an increasingly good job of making accurate weather predictions.

However, as you may have already experienced yourself, there is a big difference between local and regional weather. It simply means that there are pockets of smaller weather patterns within a larger regional weather system. 

For example, your home or neighborhood may experience a very different kind of weather than the rest of your city or state is experiencing.

(If you are interested, you can read more about the difference between local and regional weather in this article.)

Ambient Weather WS2902 Osprey Weather Station

Here the forecasting capabilities of a good home weather station comes in very handy. For example, the Ambient WS-2902A station, with its large number of internal and external sensors, does a great job of predicting the weather in your area for the upcoming hours.

Even the budget-orientated La Crosse 308-1414B, with its limited amount of sensors, is doing a surprisingly good job at predicting short-term weather, especially if you consider that its indoor and outdoor sensors only measure temperature and humidity.

As I mentioned numerous times in other posts on this website, there are three weather elements that are vital for making an accurate weather forecast:

  1. Temperature
  2. Humidity
  3. Barometric Pressure

Through research and personal experience, I discovered that the measurement of these three components is the minimum requirement for a precise weather forecast. This is what makes the accuracy of the Lacrosse station so impressive, lacking barometric sensors. 

In conclusion, a home weather station is much better at making a short-term (up to 12 hours) weather prediction of weather conditions in your specific location than a regional or broad local forecasting service can provide.

3) Remote Access

More home weather station owners are connecting their weather stations to the Internet than ever before. This is due to the built-in function of more advanced stations to quickly connect to a local internet connection, like a wireless router.

This function has two significant advantages, namely remote access to your weather station readings, and the ability to integrate your device into a global network and share your data. The latter benefit also allows you to contribute to global forecasting networks.

1) Remote Access To Your Weather Station

Remote access is a powerful feature. The Ambient WS-2902A weather station, for example, is connected via WiFi to my Internet router. This function allows me to connect to Ambient Weather's own network, called Ambientweather.net.

I can access this site from anywhere in the world from any device with an internet connection. It not only shows you all the atmospheric conditions the weather station is currently measuring but also keeps a log of all the weather the device ever recorded.

(This allows one to track and compare weather conditions over months and years, which enables you to establish weather trends, making local forecasting even more accurate.)

2) integrating Your Device Into A Global Network And Sharing Weather Data

This function is a perfect example of how valuable and effective the cooperation of thousands of weather station owners are in contributing to a very accurate global forecasting system.

Remote Access

Many home weather stations, like the Ambient WS-2902A, can be registered on a global forecasting network like Weather Underground (Wunderground) and weathercloud.net.

At the time of writing, Weather Underground already had more than 250 000 weather stations connected to their network. They use all the data from each station to assist in creating surprisingly accurate predictions, especially local weather forecasts.

As a true weather enthusiast, there are few things as satisfying than knowing that your own weather station is part of a global network that collaborates to create one of the best forecasting systems available today. 

4) Ease Of Use

Modern weather stations are extremely easy to install and operate. Most come with extensive written or online instructions that are easy to follow. If that is not sufficient, the chances are very good that you will be able to find a YouTube tutorial posted by a user.

Some weather stations with more extensive external weather sensor array will require more time and effort to assemble. It may seem intimidating at first, but by following the instruction, it is a relatively painless task. 

The Ambient WS-2902A is an example of such a setup. The La Crosse 308-1414B, on the other hand, has a single compact outdoor sensor unit that one can simply stick or screw into a wall. Either way, it is a fairly straightforward process.

The indoor display units are a breeze to set up. Instructions are provided, but in most cases, the onscreen setup wizard quickly takes you through the installation process. It is the case with both weather stations used as an example in this post.

Viewing and changing elements on the displayed units are also simple, as each symbol and value is clearly marked and logically laid out. Even if the sheer number of information on the screen may seem overwhelming, you will get used to it in no time at all.

5) Convenience And Comfort

The convenience of owning a home weather station should start to become evident by now. Without leaving the comfort of your home (and sometimes even your bed), you can quickly gauge the weather conditions outside, as well as the indoor temperature and humidity.

The ability to know what the conditions outside your home are like without having to brave potentially scorching hot weather or freezing cold first provides a substantial level of comfort and convenience.

This benefit not only allows you to dress accordingly and make any other necessary preparations, but weather stations with forecasting abilities also allow you to better plan your day.

6) Remote Access

We already touched on this subject when discussing Global Integration And Sharing Of Data. Most modern advanced home weather stations, regardless of make, have their online network on which you can register your device.

Global Communication

This function allows you to see whatever the atmospheric conditions are like at your home from any location in the world where you have access to the Internet. It is available on your laptop, PC, phone, or tablet.

I already pointed out how Ambient Weather allows the WS-2902A to connect to its online network. It is by no means the only manufacturer that provides its own online network.

Any device that a user connects to Wunderground can also be accessed worldwide, and you can read all your current weather readings in detail directly from their page.

One more advantage of remote access is the ability to control your smart home to adjust to changing weather conditions. It may be a relatively recent development, but by having your devices connected to a smart home network, you make any adjustments from anywhere.

The Ambient WS-2902A already has IFTTT functionality, meaning it can integrate with your smart home system. It allows you to set up devices in your home to respond if certain weather condition is met (like closing the blinds, switching on the aircon, etc.)

7) Affordability

Weather stations don't just come in all shapes and sizes, but also vary from extremely affordable to relatively expensive, depending on your specific requirements.

It is clearly evident from simply looking at the price difference between the two weather stations used as examples throughout this post.

The more budget-orientated La Crosse Technology 308-1414B device is available for around 50 Us dollars. On the opposite side of the spectrum, the advanced  Ambient Weather WS-2902A Osprey will set you back approximately 150 US dollars. 

There are even cheaper as well as more expensive home weather stations on the market. Depending on what you are looking for in a meteorological device, you can find a basic system for as little as 8 dollars, to a comprehensive high-end station for 1 000 dollars.

​The two devices used in this post are by no means the best available by any means. They are just two examples of weather stations that do what they are supposed to do very well. There is a multitude of instruments out there that are as good or maybe even better.

This means that whatever your needs, there will be a home weather station you can afford and meet most, if not all of your requirements.


After reading through all the benefits laid out in this post, you should be able to decide for yourself if you need or can really benefit from owning a home weather station. As the post clearly showed, there are numerous advantages to a variety of different requirements.

If you are still unsure, the following guideline may help. If you feel you need or can benefit from three or more of the advantages listed in this article, you should seriously consider the possibility of owning your own weather station.

You can start with a very affordable system that won't even put a dent in your pocket. See how well it works for you, and take it from there.

As I already pointed out, the two systems used as examples in this article are by no means the best or only quality weather devices available. In the Recommended Resources section, I already examined other weather stations worth looking at more closely.

In the future, I will share my findings in a comprehensive post whenever I obtain and start using a new weather station.

The aim of this article was to highlight the most important benefits and clear up any confusion when it comes to these weather devices. I trust it helped you in deciding if you've been sitting on the fence or wondering if you really need a home weather station.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


What Is St Elmo’s Fire?

What Is St Elmos Fire

It is not unusual to notice a seemingly inexplicable flame or light in the sky. Countless cases were documented throughout the centuries. Very often, the "unexplained" have a scientific and simple explanation.

There are various sources of light forming in the atmosphere that are well-known meteorological phenomena. Examples include occurrences like lightning, the aurora borealis, the green flash during sunsets, and noctilucent clouds in the evenings.

One such event creates a blue flame-like glow at the edge of a relatively sharp object and is called St Elmo's Fire. It often gets mistaken for other natural phenomena like fire or ball lightning, although it is a completely unique occurrence.

This article examines what this phenomenon is, provides a brief history, and explains how it develops in the atmosphere.

St Elmo's Fire Definition

The word fire, in St Elmo's Fire, can be very deceiving. Although the blue glow that forms as a result of this phenomenon may resemble a blue flame, the process itself has nothing to do with any type of fire.

Before examining how this occurrence is formed, one needs to have a clear definition of what precisely it is first.   

What Is St Elmo's Fire?

What Is St Elmo's Fire

St Elmo's Fire is a meteorological occurrence where a pointed object creates an electrical discharge in the form of a blue plasma in a highly charged electrical field. 

The illuminated plasma is the result of a process called corona discharge.

The blue glow whose shape sometimes resembles a form of fire or lightning is often accompanied by a hissing or buzzing sound. (Very much like the buzzing of neon light, which is basically the same process.)

It was already made clear that there is no relation between the blue glow synonymous with this event and incidents actual fire. Although they have similar characteristics, St Elmo's Fire is also not a form of lightning, though it has been mistaken for ball lightning in the past.

The name and history imply that this phenomenon mostly applies to maritime-related activities (more on that in the next section.) It has been shown that, however, that St Elmo's Fire can occur anywhere over land as well, If all the necessary components are in place.

As it is clearly a unique occurrence, a thorough explanation will be needed to understand how this phenomenon occurs. We will address this issue shortly, but first, a short history that will clarify the name and origin of the name, St Elmo's Fire.

A Short History Of St Elmo's Fire

Some of the first and oldest accounts of this phenomenon recorded were by sailor over the last few centuries that observed the strange glow at the top of their sailing ship's masts.

Saint Erasmus

The word "St Emo," refers to St Erasmus, a Christian bishop who lived during the Third Century. After his death, he became regarded as the patron saint of sailors.

The appearance of the blue flame-like glow on ship's masts was seen by sailors as a good omen, as they believed it indicated the presence of St Erasmus to guide them through dangerous times at sea. As a result, the blue discharge became known as St Elmo's Fire.

The fact that the phenomenon usually appears near the end of thunderstorms cemented the belief sailors had about it being a good omen since they started to associate with the end of bad and stormy weather.

How Does St Elmo's Fire Occur?

Although it seems to appear out of the blue, a couple of elements need to be in place for this event to occur:

  • A Highly-Charged Electrical Field
  • Narrow And/Or Pointed Pointed Object

In an atmosphere, like the one created during a thunderstorm, friction between particles causes a build-up of particles, leading to an increase in electrons in the air. It creates a highly charged electrical field that stretches all the way to the ground.

Sharp or pointed objects concentrate these highly-charged electrical fields, creating a discharge where air molecules get torn down to form plasma (as atoms are being stripped of their electrons). This process is better known as a corona discharge.

(A corona discharge is a process through which an electrical discharge causes air to be ionized. Ionized air is just another term for plasma.)

Sharp Object And St Elmo's Fire

During this process, illuminated plasma is created that hovers around the object where the discharge took place and can last for several minutes. Objects can include anything from cathedral towers, ship masts, the tip of an airplane wing, and even the horns of cows.

The light created has a blue or violet color since this is the color that oxygen and nitrogen emit when a discharge takes place in the atmosphere.

This exact same process takes place in neon lights where the discharge gets controlled to allow the illumination of plasma to continue permanently. It explains why the buzzing sound that accompanies St Elmo's Fire is similar to the sound emitted by neon lights.

Is St Elmo's Fire Dangerous?

There have been few if any reports of people coming in actual contact of being engulfed by St Elmo's Fire. It usually occurs on taller sharp objects like ship's masts and church towers.

Even if a human came in direct contact with this phenomenon, though, they would usually experience no more than pricking sensation. What is much more dangerous, though, is the type of event that accompanies these conditions.

St Elmo's fire occurs in the same type of electrically charged atmosphere that causes lightning to occur. If you observe the former, it may be an indication that a lightning storm is imminent or nearby. It should serve as a warning to take cover.


If you search the term on Google, St Elmo's Fire usually yields results referring to the 1980's movie with the same name. Unlike the film, it is a very real meteorological event and dates thousands of years back.

As this article explained, the mysterious blue flame-like glow that appears around sharp objects is not as inexplicable as many first time observers may think. In the most simplistic terms, it is no more than an electrical discharge that creates a body of illuminated plasma.

This post explained what St Elmo's Fire is, how it occurs, and briefly touched on any potential dangers it may pose.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


Atmospheric Absorption – Shielding The Planet From Solar Radiation

Atmospheric Absorption

The Earth gets bombarded by an incredible amount of solar radiation on a daily basis. It is responsible for illuminating the planet, as well as causing the surface and oceans to heat up. 

It is essential for the continual existence of all life on Earth. If the full amount of solar radiation is allowed to reach the surface unfiltered, though, it will be deadly and cause complete devastation.

A large portion of electromagnetic energy is scattered, refracted, diffused, and reflected by the surface and atmosphere. A significant amount of radiation is also absorbed by the atmosphere, a process called Atmospheric Absorption.

This article examines what atmospheric absorption is, how it occurs, and what parts of solar radiation are affected.

Atmospheric Absorption Definition

From the introduction, it is clear that atmospheric absorption forms a significant and essential part of the way solar radiation gets regulated by the planet. To understand how this process works, atmospheric absorption needs to be more clearly defined.

What Is Atmospheric Absorption?

What Is Solar Absorption

Atmospheric Absorption is the process through which gases and small particles in the atmosphere absorb a large percentage of solar radiation.

The sun's radiation consists of a wide range of light in the electromagnetic spectrum, from short-wavelength x-rays on the one side to long-wavelength radio waves on the opposite side of the spectrum.

The three most important forms of solar radiation that reach and impact the Earth is:

  • Visible Light 
  • Infrared Light
  • Ultraviolet Light.

Visible light forms roughly half the total amount of solar radiation reaching the atmosphere.

Atmospheric absorption is responsible for a significant portion of this solar radiation not reaching the surface of the planet, specifically infrared and ultraviolet light. 

Solar Spectrum

The Solar Spectrum Showing The Absorption & Transmission Of Different Wavelengths

Of the three primary components that make up solar radiation, visible light is the only one that reaches the planet's surface without any significant amount of absorption or filtration taking place.

In contrast, infrared and ultraviolet light gets subjected to a significant amount of absorption in the atmosphere. In the next section, we will discuss how this takes place.

How Atmospheric Absorption Occurs

The atmosphere absorbs 23 percent of all incoming solar energy. It does so through the ability of specific gases and small particles to absorb different wavelengths of radiation in the solar spectrum.

The regions in the spectrum that travels through the atmosphere without much absorption and reaches the planet's surface relative unaffected are called atmospheric windows. Visible light falls within this region.  

The parts of the electromagnetic spectrum that gets absorbed by the atmosphere are known as absorption bands. Infrared and ultraviolet light are the two biggest sources of radiation fall within this adsorption range.

The three most significant gases responsible for absorbing solar radiation is:

  1. Water Vapor (H₂O)
  2. Carbon Dioxide (CO₂)
  3. Ozone (O₃)

The way in which these gases absorb solar radiation is by a form of energy exchange in which gas molecules turn incoming light energy into heat. As a result, the atmosphere experience a rise in temperature where absorption takes place.   

Carbon Dioxide

Water vapor is responsible for absorbing the largest amount of solar radiation. Combined with carbon dioxide, water moisture is mainly responsible for the abortion of infrared radiation that sits on the side of the electromagnetic scale comprised of longer wavelengths.

The largest concentration of ozone is found in the stratosphere. It is here in the ozone layer that the highest percentage of ultraviolet light gets absorbed (which sits on the side of the electromagnetic scale comprised of shorter wavelengths.)

UV light consists of Ultraviolet-A, Ultraviolet-B, and Ultraviolet-C rays. Of these three, Ultraviolet-C is by far the most dangerous. However, ozone absorbs more than 90 percent of this form of ultraviolet light.

Ozone also absorbs around 50 percent of Ultraviolet-A, and 90 percent of Ultraviolet-B radiation. The 10 percent of UV-B that does reach the Earth's surface is enough to still pose a significant threat to human health.

It should be noted, however, that even though the gases mentioned here are responsible for absorbing a large amount of solar radiation (that can be extremely dangerous to all life on Earth), it is not the only source for preventing solar radiation from reaching the surface.

Dust and other small particles are the primary sources responsible for scattering and absorbing the total effective amount of solar radiation. It is through this process that the most significant impact of solar radiation is diminished.

Importance Of Atmospheric Absorption

It should be self-evident from the information already provided in this post just how crucial atmospheric absorption is to the survival of all life Earth.

To emphasize the importance of this process, two key areas will be highlighted where the absence of atmospheric absorption will be catastrophic to the planet.

1) Ultraviolet Radiation Protection

Almost no Ultraviolet-C light reaches the planet's surface since more than 99 percent gets absorbed by ozone in the atmosphere. UV-C light is the most dangerous form of ultraviolet radiation and can cause severe burns, eye damage, and skin cancer.

Even if only 50 percent of UV-C radiation were allowed to reach the surface, the result would be catastrophic for all life on Earth, making outside exposure to the sun almost impossible. 

(The same applies to Ultraviolet-B radiation, where around 90 percent of this light is blocked by the atmosphere.)

2) Warming Of The Planet's Surface

Infrared Light

Infrared light is responsible for warming the surface of the planet, which is essential for the existence of every biological organism (humans included.)

A fine balance exists between the amount of heat the Earth receives and the amount that gets radiated back into space. A large percentage of IR light gets absorbed by water vapor and carbon dioxide in the atmosphere.

In the absence of this absorption, heat will build up at a much faster rate than it can be expelled, which will make the planet uninhabitable in a very short space of time.

Everything in this section has already been mentioned throughout this post but was worth emphasizing to highlight just how crucial the atmospheric absorption process is.


From this post, it is clear that although it not such a well-known topic, atmospheric absorption forms a crucial part of the Earth's global climate and weather systems.

This article focused on explaining what atmospheric absorption is, how it takes place, and its importance to the planet and all life on it.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


Canyon Wind: What It Is And How It Forms

Canyon Wind - What It Is And How It Forms

Wind is usually the result of a change in air pressure where other elements of weather like temperature all play a role. In some cases, physical changes on the Earth's surface can also create certain winds.

Variations on the planet's surface like steep elevations (mountains), valleys, plateaus, and canyons can play a significant part in the formation of weather. One weather element that is especially prone to variations on the surface is wind.

This article will focus on the role canyons (or canyon-like features) play in the formation of a type of wind called a canyon wind.

A canyon creates a unique environment where not one, but two different types of canyon winds can form. This post will examine what they are and how they are formed.   

Canyon Wind Definition

As the introduction already eluded to, a canyon's physical attributes allow for the formation of two distinct winds, both of which can fall under the term, canyon wind.

It is, therefore, crucial to have a clear and concise definition of these phenomena before exploring their creation and characteristics in more detail:

What Is A Canyon Wind?

What Is A Canyon Wind

A canyon wind can be defined as:

a) A nocturnal wind that blows down the cold canyon walls during the evening as a result of the Earth's gravitational force.


b) A strong low-level wind that forms as a result of air being forced to accelerate in the narrow space between the canyon walls.

From the definition alone, it is already evident that the two types of wind that is the result of an interaction with a canyon, are distinct and very different from each other.

The wind that flows down the canyon walls in the evenings is also known as a mountain breeze, which may be more familiar to many readers.

The low-level wind that is the result of air being forced to flow through a confined space between canyon walls is also known as a gap wind.

The best way to gain a clear understanding of both winds is to examine the development and characteristic of each one individually.

Development Of A Canyon Wind (Mountain Breeze)

During the day, the sun heats the floor and slopes (walls) of a canyon. In turn, the heated surface warms up the air directly above it, causing it to expand and rise into the atmosphere. (This phenomenon is often referred to as a valley breeze.)

Mountain Breeze

In the evening, the surface of the canyon walls cools down more rapidly than the surrounding atmosphere. The colder surface cools the air above it, causing it to contract and become denser as its temperature continues to drop.

The dense cold air is heavier than the surrounding atmosphere and starts to flow down the slopes to the canyon floor. The resulting airflow is called a canyon wind (often better known as a mountain breeze.)

Canyon winds can be quite strong due to the steep gradient of canyon walls. Where the canyon winds from the two opposing walls converge at the bottom, they can combine and follow the downward slope of the canyon floor as a single strong air current. 

Development Of A Canyon Wind (Gap Wind)

As discussed earlier, a canyon wind in the form of a mountain breeze is not the only form of canyon wind that occurs.

When a low-level wind encounters a geological obstacle like a mountain, it needs to find a way past it. Since this type of wind is usually only a few hundred meters high, it is not always possible to maintain momentum and mass by flowing over the mountain.

When it encounters a gap in the mountain, like a canyon, the wind is forced to funnel through the relatively narrow channel created by the canyon. To maintain mass and momentum, air needs to accelerate, producing strong winds in the process.

Gap Wind

The channeled wind that forms as a result of the funneling of air through a narrow space is called a canyon wind (sometimes better known as a gap.)

These types of canyon winds can reach high velocities of up to 93 km/h (58 mph). The speeds was thought to be at their strongest in the narrowest part of the canyon (called the Venturi Effect).

Recent studies managed to conclude that this not the case, since canyons are open at the top, allowing air pressure to force wind to rise over the mountain. They determined that the greatest wind speeds occur at the exit of a gap in the mountain (the canyon mouth.)

This type of canyon wind is not just limited to natural geological phenomena but also man-made structures..

Urban Canyon Effect

In densely populated urban areas, specifically city centers with tall buildings flanking city streets, a phenomenon identical to a canyon wind (gap wind) occurs quite frequently.

When low-level winds encounter a city center with its "wall of buildings," the narrow opening provided by streets acts as a canyon. Similar to canyons, the wind accelerates as it is channeled through this small gap, creating what is called an urban street canyon.

This urban canyon effect occurs when the wind hits the densely grouped buildings at a parallel angle, where the streets that are running in the same direction as wind act as an escape route through which the wind can be funneled.

The urban canyon effect forms part of a broader meteorological phenomenon that occurs in large metropolitan areas called an Urban Heat Island.


What is clear from this article is that geological structures on the Earth's surface can play a huge role in the formation and modification of air movement. In the case of canyon winds, these structures can even result in more than one type of wind.

Canyon winds are unique in that their structure allow them to create two distinctly different types of winds with their own characteristics. Also known as mountain breezes & gap winds, these forms of canyon winds can occur in similar environments under different names.

This article focused on the two types of canyon winds, how they develop, and also highlighted how urban environments could recreate the effect of certain canyon winds.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


Ephemeral Stream: What It Is And How It Occurs

Ephemeral-Stream - What It Is And How It Occurs

From the largest rivers to the smallest creeks, all play a crucial role in supplying the land, animal, and human population with vital resources. It even applies to the most modest temporary stream.

Not all rivers and streams continuously flow throughout the year. Some of them are seasonal, and some only flow during specific events. No matter what their size or frequency, they all form part of the Water Cycle that distributes and cycle water around the planet.

One such temporary stream is called an ephemeral stream. It does not flow often and only for a short duration during specific occurrences. Yet, it is still just as an important source of water than any extensive permanent river system. 

This post examines what an ephemeral stream is, how it forms, and how it differs from other types of streams and rivers.

Ephemeral Stream Definition

Most major river systems and larger streams flow throughout the year, meaning they are perennial. (Like the Rhine in Europe, the Amazon in South America, and the Nile in Africa.) An ephemeral stream, though, is not only transitory but is not even a seasonal occurrence.

To be able to describe how and why this type of stream form, one needs to gain a clear understanding first of what precisely an ephemeral stream is:

What Is An Ephemeral Stream?

What Is An Ephemeral Stream

An ephemeral stream is a temporary stream that only flows for a brief period as a direct result of precipitation.

It occurs mainly in arid and semi-arid regions where rainfall occurs infrequently.

The word, ephemeral, is derived from the 16th Century Greek word "ephēmeros," which aptly means "lasting for a very short time." And it is the brief occurrence of an ephemeral stream that is its most defining characteristic.

Since these streams occur for such a brief period, it does not have the time to carve out a deep and wide channel, as is the case with a perennial river. It also occurs in predominantly dry regions, where the groundwater table forms much deeper below the surface.

As a result of these two factors, ephemeral streams occur above the groundwater table, compared to more permanent streams and rivers, which riverbeds lie below the water table. The significance of the groundwater table height will become clear in a later section.

How Ephemeral Streams Formed

In arid or semi-arid regions, precipitation occurs very infrequently. As a result, when a large enough amount of rainfall does occur, it often forms a temporary stream on the surface.

The stream can create a new path, or follow an existing channel (also called a dry wash) established by previous occurrences of ephemeral streams.

The paths these streams follow can link up with larger networks of intermittent or perennial streams and rivers. 

Dry Stream Bed

They can also continue to flow for a short distance, before evaporating completely without reaching any significant point or being absorbed into the soil to form groundwater.

Ephemeral streams flow for a limited time and dry up quickly, only leaving a dry stream bed behind. These dried-up channels are sometimes more accurately described as arroyos, which are synonymous with the arid and semi-arid areas where ephemeral streams occur. 

It is important to note that the ephemeral stream and the channel (arroyo) if flows in are not the same thing. The stream itself is the actual flow of water that is transitory, while the channel it flows in remains a permanent fixture of the landscape.

Importance Of Ephemeral Streams

It is only natural to conclude that ephemeral streams play an insignificant role in contributing to the Water Cycle and have any other beneficial influences on the environment. Such a conclusion can not be further from the truth.

These streams play an essential role in supplying fresh and maintaining existing resources in at least three different ways:

1) Fresh Water Supply To Perennial Water Networks

Even though ephemeral streams only flow during or after a spell of rain, the combination and frequency of these streams have a huge impact. In fact, they contribute the vast majority of freshwater to the entire river network in arid and semi-arid regions.

For example, 95% of all streams in the Arizona Dessert are seasonal, of which a substantial amount are ephemeral. Even in wetter regions with frequent rainfall, it is estimated that more than 50% of the total stream network comprises of temporary streams.

2) Supply Of Fresh Sediment To  Downstream Regions

Fresh Sediment Supply

During extended dry spells, dried-up stream beds (arroyos) builds up a layer of soil, which nutrient content hasn't been depleted by vegetation growth. 

The organic matter created by dead animals and insects, as well as the remains of dead plants, also accumulate in arroyos, further enriching the nutrient content of the soil.

When a spell of rain causes an ephemeral stream to flow, it carries this nutrient-rich soil downstream, where it gets deposited on riverbanks and the surrounding areas, replenishing the land with much needed fresh sediment.

3) Maintenance And Replenishment Of Groundwater Tables

As the arid and semi-arid regions, where ephemeral stream occurs, don't contain much moisture, the groundwater tables are situated much further below the surface than in wetter areas with an abundance of rain.

When a substantial amount of rain falls, it allows ephemeral streams to contain a large enough volume of water to have some of it absorbed by the ground to replenish its deep water tables.

It can also flow far enough to connect with more permanent (perennial) river networks downstream. It not only supplies these systems with additional water but also assists in maintaining and replenishing their groundwater tables as well.

The Difference Between Ephemeral And Intermittent Streams

Some confusion exists among observers about the difference between ephemeral streams and intermittent streams since they are both regarded as temporary streams.

Ephemeral streams have already been clearly defined as temporary streams that only flow as a direct result of precipitation. The depth of their groundwater tables also means that they can't access this water source to sustain their flow in any way.

Difference Between Ephemeral And Intermittent Streams

Intermittent streams, however, differ in more than one way. They are often seasonal, meaning that although they don't flow throughout the year, they receive a steady supply of water during the rainy season, which allows them to flow for sustained periods.

They also have deeper and more prominently defined river beds, combined with shallower groundwater tables as a result of the availability of more water. It allows the river beds to lie below the water table, allowing them to access groundwater to sustain their flow.


What became clear through this article, is how a seemingly insignificant occurrence can play a significant role in a much more extensive network.

An ephemeral stream is not only temporary but only flows for a brief period during or after a spell of rain. Yet, in many regions, they account for the vast majority of water supply to major river networks, enabling them to flow throughout the year.

This article explained what an ephemeral stream is, how it forms, and its importance to larger, more perennial water networks. It also addressed and clarified the difference between an ephemeral and intermittent stream.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


Cap Cloud – What It Is And How It Differs From Lenticular Clouds

Cap Cloud - What It Is And How It Differs From Lenticular Clouds

Clouds literally come in all shapes and sizes. The majority we know is a result of different weather elements, like heat, wind, and moisture. Some, though, occur as a result of variations on the Earth's surface.

Variations on the planet's surface influence a variety of meteorological occurrences like wind, temperature, and yes, cloud formation. Especially elevations and dips on the surface play a significant role in the development of certain clouds. 

One type of cloud that is a direct result of the physical elevation in terrain is called a cap cloud. In this post, we look at what cap clouds are, how they form, and how they differ from the more familiar lenticular clouds.

Cap Cloud

As mentioned in the introduction, a cap cloud is the result of a change in physical terrain, but this is not the only factor at play in the formation of this cloud system.

What Is A Cap Cloud?

Before looking into how a cap cloud is formed, one must first define what precisely it is, and describe its characteristics in more detail: 

What Is A Cap Cloud?

What Is A Cap Cloud

A cap cloud is a stationary orographic cloud that forms over the peak of a mountain, where moist air is forced up the windward slopes and condensates as it flows over the top.

This cloud is characterized by its unique mushroom or upside-down saucer shape, and can always be found on top or above a mountain peak.

It is not that uncommon to see two cap clouds on top of each other, hovering over the same mountain top. It occurs typically when a layer of dryer air separates two layers of moist air.

How Cap Clouds Form

Cap clouds form as a result of orographic cooling (which is part of the Orographic Effect). As prevailing winds push moist air against a raised terrain like a mountain, it forces the layer of air to rise against the slopes.

As the air rises, it starts to cool down. It continues to cool down until it reaches dew point and condensation takes place near the top of the mountain. As a result, the air flowing over the mountain top creates the flat, dome-shaped cloud that is the trademark of a cap cloud.

The raised terrain does not only cause the air to rise on the windward side of the mountain, but as it starts to descend down the leeward slopes, it also creates a wave in the airflow. And it is here where lenticular clouds come into play.

Lenticular Clouds

The wave formed in the wake of the air lifted over an elevated terrain forms the foundation for the occurrence of lenticular clouds.

What Is A Lenticular Cloud?

As with cap clouds, one first needs to get a clear understanding of the definition of a lenticular cloud before looking into how these clouds develop:

What Is A Lenticular Cloud?

What Is A Lenticular Cloud

A lenticular cloud is a stationary cloud that occurs high in the troposphere on the leeward side of a mountain. It is characterized by its saucer or lens-like shape.

It forms on the crest of a wave that is the result of air forced to lift due to a rise in physical terrain. Its alignment is usually perpendicular to the direction of air movement.

As mentioned in the description, lenticular clouds form at a high altitude in the troposphere. This is mainly due to the elevated terrain, specifically mountains, that is responsible for creating the conditions favoring the formation of these clouds. 

A few elements need to be in place to form the ideal conditions for lenticular clouds to occur. The creation of wave movement on the leeward side of a raised terrain is the crucial element in the formation of these clouds.

The saucer or lens-like shape is another unique characteristic of lenticular clouds. Since it does not appear close to the surface, it is not often visible from the ground. As a result, it is often mistaken for a UFO (Unidentified Flying Object) or another artificial object.

The layered (pancake) shape of the cloud is the result of multiple layers of cold air reaching dew point at the crest of downwind waves. The crucial role these downward waves play in the formation of lenticular clouds will become evident in the next section.

How Lenticular Clouds Form

For a lenticular cloud to form, three elements need to be present and in place:

  • Adequate Moisture In The Air
  • Prevailing Wind
  • Formation Of A Wave In The Air Movement On The Leeward Side Of A Mountain

As mentioned earlier, it is this wave of air that is primarily responsible for the formation of a lenticular cloud.

After the formation of a cap cloud, the air which lifted on the windward side of a raised terrain dips on the leeward side. More importantly, it creates a continuous wave in the air moving downwind.

How Lenticular Clouds Form

The wave consists of a series of crests and troughs continuing downwind. When moist air reaches the crest of a wave, and the temperature drops below dew point, condensation takes place, which allows for the development of a lenticular cloud.

When the prevailing wind persists, the crests and troughs in the wave of air continue to form downwind, which can result in a series of lenticular clouds to form. These formations are better known as a wave cloud.

The clouds seem to remain stationary, but there is a constant flow of air through them. The reason they "stay in place" is that the air dips below dew point at the crest of the wave, allowing the cloud to form. When the wave dips down, it evaporates as the air warms up.

Difference Between Cap Clouds & Lenticular Clouds

What will have become evident during the description of cap and lenticular clouds is that their formation is almost identical. The only difference is that a lenticular cloud forms on the wave of air created due to forced elevation on the leeward side of a mountain.

Several articles and papers clearly state that cap clouds are actually lenticular clouds, due to the almost identical formation process and similar cloud shape. Technically, this statement is correct, and a cap cloud can be classified as a lenticular cloud.

However, from a practical standpoint, and when described in layman's terms, there are subtle but significant differences between the two that can be summarized as follows: 

  • While cap clouds occur directly over a mountain peak, lenticular clouds usually form on the leeward side of the mountain.
  • Cap clouds have a flat, dome-shaped form while lenticular clouds have a layered or stacked shape in the form of a lens or saucer.

As already stated, these are subtle but significant differences.


It is clear that there can be some confusion when discussing cap clouds and lenticular clouds and why they are often seen as the same type of formation. This post managed to highlight the small but notable differences between the two.

And that was the aim of this article: To explain what cap clouds are and how they form, and how they differ from lenticular clouds in formation and shape.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


Adiabatic Process: What It Is And How It Occurs

Adiabatic Process-What It Is And How It Occurs

Air pressure plays a vital role in meteorology and can be found in a wide variety, if not almost every possible weather event. In a confined space, air pressure plays a unique role, and not only in meteorology.

Think of the internal combustion engine (ICE) used in traditional motor vehicles. Without the air pressure created in the combustion chamber to drive the piston inside a cylinder, the ICE will not be able to operate.

Similarly, the steam engine, which was widely used during the early stage of the Industrial Revolution, operates on the same principle. Heat is applied to a confined chamber, causing moist air inside to expand, which in turn forces cylinders to move up and down.

The three factors that play an essential role in both these processes are heat, air pressure, and a confined body of air. And it is these three factors that also create a similar process in meteorology. It is called the adiabatic process.

As already shown, the adiabatic process is used in a variety of different disciplines. However, this post will focus exclusively on the adiabatic process as it applies to meteorology.

Adiabatic Process

During the introduction, you already received plenty of clues as to what the adiabatic process entail and was probably able to form a vague idea of its definition.

It is essential, however, to get a clear and concise definition of what precisely the adiabatic process is, before examining how this phenomenon takes place.

What Is The Adiabatic Process?

Adiabatic Process

The adiabatic process describes the heating or cooling of a body of air without any form of energy exchanged between this system and the surrounding environment.

Temperature change within a pocket of air mainly takes place due to its compression or expansion as a result of a change in air pressure in the surrounding atmosphere.

One of the most vital characteristics of the adiabatic process to highlight is the fact that the process takes place in relative isolation. It simply means that no mixing of air takes place between the body of air and the surrounding atmosphere.

There is a second important characteristic of the adiabatic process in meteorology. And this is that it occurs as a result of the surrounding atmosphere's pressure on the air pocket, specifically in adiabatic cooling and heating.

Now that it has been established that the heating and cooling of a body of air is one of the primary impacts of the adiabatic process, the focus should now be on how these cooling and heating processes take place.

Adiabatic Cooling

Adiabatic cooling is a natural occurrence that takes place in the lower atmosphere and is primarily due to a change in altitude. Usually, the altitude change occurs through one of two processes. These two processes are:

  1. The Heating Of A Layer Of Air At The Surface
  2. Forced Elevation Due To A Rise In Geographical Terrain

1) The Heating Of A Layer Of Air At The Surface

Adiabatic Heating

When solar radiation heats the Earth's surface, it also warms the air above it. The warm body of air is less dense (and lighter) than the surrounding air and starts to rise. As it gains altitude, it continues to move into areas with less density, causing it to expand even further.

Any body of air contains a large number of molecules that vibrate and bounce off each other. The closer these molecules are to each, the quicker they vibrate and collide with each other. We observe this as a rise in temperature. 

In this case, however, the body of air expands as it gains altitude where the atmosphere has less air pressure. It means the molecules move further away from each other, becoming less energetic with fewer collisions occurring, resulting in a drop in temperature. 

2) Forced Elevation Due To A Rise In Geographical Terrain

Sometimes adiabatic cooling is not the result of the heating of a surface. When prevailing winds (like a sea breeze blowing inland) are present, a layer of air is moved horizontally but sometimes encounters a raised terrain like a mountain or large hillside.

As a result, the layer of air is forced to rise against the mountainslopes. As the altitude increases, the atmospheric pressure becomes less, allowing the air pocket to expand and cool down in the same way a body of warm air rising from the surface would. 

This form of adiabatic cooling is also known as orographic cooling, which forms part of the Orographic Effect. To find out more about this phenomenon and how it occurs, you can read the in-depth article here.

The rate at which temperature drops as altitude increases is called the adiabatic lapse rate. The amount of moisture in the air plays a role at the rate at which temperature decreases, and can be divided into the:

Dry Adiabatic Lapse Rate: When there is little or no moisture present in the air parcel, it will cool at an average rate of 10° Celsius per 1 000 meters (5.6° Fahrenheit / 1 000 Feet).

Wet (Moist) Adiabatic Lapse Rate: When a substantial amount of moisture is present in a body of air that is rising,  it will cool at an average rate of 5° Celsius per 1 000 meters (3.2° Fahrenheit / 1 000 Feet).

Please note that these figures are just average lapse rates and will vary according to more specific atmospheric conditions.

Adiabatic Heating

The adiabatic process takes place in reverse during an occurrence of adiabatic heating.

When a body of air at higher altitudes starts sinking to the ground, it gets subjected to increased atmospheric pressure as it moves closer to the planet's surface. The increased pressure causes the air parcel to compress and shrink in size.

Orographic Heating

As already discussed, when a body of air contracts, the molecules inside get energized as it starts to vibrate more quickly and collide with each other at an accelerated pace. This process manifests as a rise in temperature.

One example of adiabatic heating occurs during a heat burst when a layer of cold, dry air drops to the ground from a high altitude in the wake of a dissipating thundercloud.

Another example is part of the Orographic Effect as cold, dry air drops down the slopes on the leeward side of a mountain.


The adiabatic process plays a vital role in many fields and disciplines. It also has a significant role to play in several meteorological occurrences.

In this post, we focused on adiabatic heating and cooling and illustrated how they could impact the weather without any energy exchange with external elements like solar radiation, wind, and moisture.

The main goal of this article was to explain the adiabatic process, how it occurs, and highlighted some examples of this phenomenon.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


The Hottest And Coldest Time Of The Day – When They Occur And Why

Hottest Time Of The Day - When Is It And Why

The warmest time of the day is when the Earth receives the most solar radiation from the sun, and it is closest above your location, correct? Actually, no. Though it sounds obvious, you will be off by a few hours.

The same applies to the coldest part of the day. Both the hottest and coolest part of the day occur much later than you may think.

It does not seem to make sense since the Earth receives the most amount of solar radiation from the sun around noon (depending on your location and the time of year.) 

Similarly, the surface will keep on cooling down during the night until sunrise when it starts to receive sunlight and begins warming up. It is natural to reason, therefore, that the coldest time of the day will be just before sunrise. But this is not the case.

This article examines when the warmest and coldest part of the day is, and why they occur at these different times. It also looks at the various factors involved in these occurrences.

Hottest Time Of The Day

As already mentioned, the Earth's surface receives the most amount of solar radiation around noon, yet this is not the part of the day that is the warmest.

Before we look into why this occurs, it is important to define a clear definition first of when precisely the hottest part of the day is:

What Is The Hottest Time Of The Day?

Hottest Time Of The Day

The hottest time of the day occurs between 3 pm and 4:30 pm, around 3-5 hours after noon (when the sun is at its highest point in the sky, and the Earth receives the most amount of solar radiation.)

This delay is due to the Earth's surface receiving and absorbing heat at a higher rate than it is able to radiate until mid to late afternoon when the process reverses.

Although this summary is an accurate average to use to judge when a day will be at its warmest, a couple of factors can cause the actual peak temperature to occur earlier or later in the afternoon.

Weather elements such as cloud cover and wind can have a significant impact on peak daily temperatures. Geographical location also has an effect, where inland regions can reach its highest temperatures of the day much later in the afternoon than coastal areas.

Why The Hottest Time Of Day Occur In The Afternoon

Although the sun is at its highest point in the sky and the Earth receives the most amount of solar radiation around noon, we now know that the day's highest temperature does not occur until around 3 pm. This delay is also known as thermal response

Surface Radiation

Thermal response occurs as follows: After noon, even though the sun's radiation starts to drop, the Earth retains much of its heat while still receiving solar radiation. It means the heat building at the surface is higher than that which the planet can radiate away. 

As a result, the temperature continues to rise until the solar radiation is weak enough for the Earth's ability to radiate heat back into the atmosphere, becomes greater than the radiation it receives. And this occurs between 3 pm and 4:30.

Coldest Time of the Day

Like the hottest time of the day, the coldest time of the day occurs much later than one might expect. What makes it even more confusing, is the fact that weather forecasters often refer to daily lows that will be experienced "during the evening."

It is statements like these that backs up the common belief that the coolest time of day should occur during the night. As much as this type of thinking seems to make sense, it is not accurate at all.

As is the case with the warmest time, it is important to define when precisely the coldest time of day is first before we delve into explaining why and how this takes place:

The Coldest Time of the Day

Coldest Time Of The Day

The coldest time of the day occurs some time after sunrise.

It occurs when the sun's radiation is still too weak to warm the planet's surface at a greater rate than the Earth is radiating heat away from the surface into the atmosphere.

This may not seem to make sense at first since solar radiation is the primary source of heat and light to the Earth every day.

Take into consideration, though, that when we perceive the sun to rise on the horizon, it is still 6 degrees below the horizon (aka twilight). The atmosphere can bend light like a lens, making it appear that we receive sunlight when no actual solar radiation is yet present.

Depending on your location and time of the year, after sunrise, it will also still take the sun between 3 and 8 hours to reach its highest point in the sky and the Earth to receive maximum solar radiation after sunset.

Although these are all contributing factors, the main reason for the coldest time of the day involves the same factors responsible for the warmest part of the day, which we will address in the next section.

Why The Coldest Time Of Day Occur After Sunrise

After the hottest time of the day, which occurs around 3 pm, the Earth continues to radiate heat out into the atmosphere at an accelerated pace. At the same time, solar radiation decreases until completely disappearing around sunset.

The planet's surface continues to cool down as it radiates heat throughout the night. After sunrise, the ground starts to receive solar radiation, but it is still too weak to counteract the rate at which the surface continues to cool down as it radiates heat into the atmosphere.

Solar Radiation

The coldest time of the day occurs once the speed at which the Earth radiates heat is no longer stronger than the incoming solar radiation, and the ground starts to warm up. As already stated, this occurs some time after sunrise. 

The exact time the coldest stage of the day takes place depends on atmospheric conditions, as well as the location and the time of the year.


Although it may not have made sense in the beginning, it should now be clear why the hottest and coldest times of the day occur when they do. It also explained why the delay between the period of maximum solar radiation and the hottest time of the day takes place.

This delay occurs on a seasonal basis as well. The warmest and coldest days of the year (and the hottest and coldest months) are based on the same principle. To find out more about these occurrences, you can find the in-depth article here.  

This article aimed to examine when the warmest and coldest part of the day is and why they occur at these times. It also looked at the various factors involved in these occurrences.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


Huayco: What It Is And How It Is Caused

Huayco - What It Is And How It Is Caused

Most of you are familiar with an avalanche that causes millions of tons of snow to rush down a mountainside and bury everything in its path. In the tropics, a different but similar event occurs with potentially deadly consequences.

Regions in and around the Tropics get subjected to large amounts of rainfalls throughout the year. These include areas like the Caribbean, Southeast Asia, Central & South America, as well as the mountainous terrain of Asia. It can have deadly and devastating occurrences.

Due to the heavy torrential rain, flash flooding and mudslides occur quite frequently in these areas, especially in the high mountainous terrain of Peru. These events that are so synonymous with this part of the world are more commonly referred to as huaycos.

This post explores what a huayco is, how it gets formed, and its potentially devastating effect on its surroundings.

What Is A Huayco?

As you might have already concluded, a huayco is a mudslide, accompanied by flash flooding, which is the result of heavy rains in the mountains of Peru. It sounds simple enough, but there are, in fact, many more factors at work to create this event.

Before looking at the different mechanisms at work in the formation of this event, though, one first needs a concise formal definition of what precisely a huayco is:

What Is A Huayco?

What Is A Huayco

The term, Huayco, refers to the flash flooding and accompanying mudslides that occur in the Peruvian region of South America as a result of heavy torrential rains.

It originates high in the mountainous regions of the country, and the event is closely related to the weather produced by the El Niño phenomenon.

The weather may be the impetus that sets the process in motion but cannot act on its own. The moist, soft soil covering the ground surface, combined by the gravitational force of the steep mountain slopes, largely contributes to the development of a huayco.

In the next section, we will briefly look at the meaning of the term "huayco" and its origins before continuing to explore the formation of this occurrence.

Meaning And Origin Of The Term, Huayco

A huayco is also known as a huaico. When you look at the origin and translation of both these terms, it will become clear how accurately they describe the characteristics of this specific phenomenon.

The word, huayco, is derived from the Quechuan word, wayqu. The Quechuan language is spoken by the Quechua people living in the Andes region of Peru. The term, huayco translates to either "valley" or "depth."

The word, huaico, has a Spanish origin (the most widely spoken language in Peru.) It translates to "avalanche," a phenomenon that shares many characteristics with a huaico.

What Causes A Huayco

The Tropics, where Peru is situated, already receives a large amount of rainfall throughout the year. Occasionally, though, a weather phenomenon called El Niño causes the region to receive an abnormally high percentage of precipitation.

In short, an El Niño occurs when the warm waters of the Pacific Ocean that would normally travel west and accumulate at the coast of Southeast Asia, are forced to flow in an easterly direction and build up against the northwestern coastline of South America.

(You can learn more about the formation and characteristics of El Niño in this article.)

The moisture-rich water that builds up against the South American coast results in the largescale formation of rainclouds, which leads to a significant increase in precipitation in regions like Peru.

Torrential Rain

The increased rainfall causes riverbanks to overflow and runoff areas to exceed their boundaries. This leads to flash flooding over parts of the mountainous terrain in the land.

The dry mountain slopes of the Andes in southern Peru have little or no vegetation cover. Combined with heavy deposits of soil, they are left vulnerable and exposed to extreme weather elements. 

During an El Niño event, water from burst river banks and dried-up runoff areas, rush down the mountain slopes while picking up the loose dry soil on the ground. It continues to race down the mountain, gathering even more soil until it starts turning into a dense mudslide.

The sheer momentum and size of the mudslide allow it to pick up objects like rocks and tree trunks, creating a potentially devastating and deadly force capable of wiping out almost anything in its path. 

It is this deadly combination of mud, rock, trees, (and other objects mixed in) that can completely overwhelm and cover vegetation and small villages at the bottom of the mountain slopes. (More on the impact and effects of a huayco in the next section.)

Contributing Factors To Huayco Formation

Although they have already been mentioned in passing, three main contributing factors help to create very favorable conditions for a huayco to occur in the Peruvian region of South America:

  1. Location of Peru
  2. Climate of Peru
  3. Geography of Peru

Although none of these factors cause a huayco by themselves, each one contributes and combined, they create a very favorable environment for the occurrence of this event.

1) Location of Peru

Peru is situated in the Tropics, just south of the Equator. The western part of the country borders the west coast of South America, which makes it highly susceptible to the weather that occurs over the Pacific Ocean (including the El Niño Effect.)

To the east, the Andes Mountains raise the terrain where higher rainfall creates lush vegetation that forms part of the Amazon Rain Forest.

2) Climate of Peru

Since Peru experience a tropical climate, it is subjected to large amounts of rainfall throughout the year, especially in the mountainous region to the east.

However, the influence of the Pacific Ocean to the east creates a dryer climate, while the Andes Mountains raise the terrain, creating wet & rainy weather conditions to the east of the country.

It is the contrast between the dry low-lying west and elevated east with its higher rainfall that creates a favorable environment for a huayco to develop.

3) Geography of Peru

Essentially, Peru can be broken up in three geological regions:

  • The Amazon Rain Forest
  • The Highlands
  • The Coast

The Amazon Rain Forest forms the northeastern border of Peru. Although it forms the largest region in Peru (59%), only 12% of the population lives in this region. The relatively flat landscape is covered with dense bush and trees that are so synonymous with the Amazon.

The Highlands mainly consists of the Andes Mountains with its peaks and valleys, reaching a maximum height of 6 768 meters (22 204 feet). It occupies 36% of the land, and 30% of the country's population lives in this area.

The Coast occupies the smallest part of the country (11%), yet the largest part of the population (52%) lives on this relatively small strip of coastal land. The dry, yet fertile piece of land extends from the ocean to the foothills of the Andes Mountains.

From the geographical layout of the country, it is clear to see how heavy rainfalls originating in the Andes mountains can trigger a huayco as water rush down the slopes and picks up the dry fertile ground and turn into devastating mudslides.

Effects Of A Huayco

The impact of a huayco can and usually is devastating. The widespread damage and injury (and in most cases loss of life) of largescale mudslides have already been well documented and covered in the mainstream media.

To give you an indication of the sheer size and power a mudslide, the following list of characteristics will provide some perspective:

  • Flash flooding can trigger one or multiple mudslides at a time. 
  • They vary in size, but a typical big mudslide can be 300 meters (984 feet) wide, 50 meters (164 feet) thick, and 1 600 meters (1 000 feet) long.
  • Mudslides travel downhill at around 80 km/h (50 mph) but can reach speeds of up to 322 km/h (200 mph) on steep slopes.
  • One of the most dangerous aspects of a mudslide is its unpredictability. It can occur suddenly and without warning, leaving little chance to get out of its way. 

From these characteristics, it is clear to see just how devastating a mudslide can be. The following are only a summary of the most significant types of impact a huayco can have:

1) Infrastructure Damage And Destruction

Infrastructure Damage

The sheer speed and size with which a huayco can strike any area will cause either damage or create complete destruction on a broad scale, depending on the size of the mudslide.

It can bury entire villages under meters of mud and completely destroy roads and bridges. Power lines, railroads, and other forms of information can also get washed away in a matter of minutes.

2) Injuries And Fatalities

Many villages in Peru are situated at the bottom mountain slopes. It makes them especially exposed and vulnerable to a huayco. When a mudslide does occur, it can bury an entire village, as already mentioned.

It usually leads to dozens of fatalities, with hundreds of people left injured and displaced. This is just the scenario for a single small village. When a more extensive region and more communities get effected, this number can easily more than double.

3) Loss Of Crops And Livestock

At the bottom of a slope, a mudslide can quickly spread over large areas. These include large fields of crops that are easily destroyed and can also lead to entire herds of livestock being killed off in minutes.

Since many villages live off the land and rely on their crops and livestock for survival, this can have a severe impact and leave people without food for undetermined periods.

4) Disruption Of Water Supply

Water supply and treatment facilities are also adversely affected by mudslides. Reservoirs can get damaged or destroyed. Even if they do not get demolished, the water of dams and water treatment facilities are polluted with contaminants they carry with them.

Water is the lifeblood of any community, and without it, villages and towns in affected areas will suffer and not be able to endure indefinitely.

5) Economic Cost

It should already be evident from the damage and destruction just described, but the economic impact of strong mudslides on the country is severe. It can quickly run into billions of dollars of damage.

One can easily see how a series of these events in quick succession can put a region and the entire country under extreme financial pressure.


Although mudslides occur all over the world, the conditions that create a huayco in the Peruvian region are quite unique, as was illustrated throughout this post.

This article clearly illustrated what a huayco is and how it develops. It also looked at its defining characteristics and impact on the areas it affects as well as human life.

Feel free to leave any comments, questions, or suggestions you may have. Your opinion is valued and will be attended to as soon as possible.

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

Until next time, keep your eye on the weather!


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