Archive

Category Archives for "General"

Heat Burst: What It Is And How It Forms

Heat Burst-What It Is And How It Forms

If you are one of the few people who ever experienced a sudden gust of warm, dry wind that came out of nowhere on a hot summer's night, you may just have encountered a rare weather phenomenon. 

Readers who closely follow the articles on this platform would have noticed that more recent posts focused on meteorological phenomena surrounding severe weather events, specifically those involving thunderstorms.

The majority of articles focused on events taking place within thunderclouds, as well as those occurring when these storm systems interact or work with each other in unison.

The subject of this post is yet another example of the "byproduct" of a thunderstorm. Unlike most other weather events involving these storms, though, it is not characterized by cold or wet weather. A heat burst is a rare occurrence with unique characteristics.    

This article examines what a heat burst is, how it gets formed, and also takes a look at it its specific features.

What Is A Heat Burst?

The introduction already gave away some hints of the makeup of this weather event and its formation. What precisely it is and how it develops will shortly be discussed in detail. 

Before delving in, though, it is imperative to provide a more formal and concise definition of a heat burst to provide a solid foundation to work from:  

What Is A Heat Burst?

What Is A Heat Burst

A heat burst is a sporadic meteorological event that is defined by strong gusts of dry winds accompanied by a sudden and significant rise in temperature.

This phenomenon typically occurs during the evening in the wake of a dissipating thunderstorm on warm days during the summer months.

In simple terms, a heat burst is a warm and dry gust of wind that occurs on a hot day during the summer months and usually takes place in the evening. It follows in the wake of a dissipating thunderstorm and causes a significant rise in the surrounding air temperature.  

Its formation is similar to that of a microburst, but as you will soon learn, a few subtle differences create a very different outcome.

How A Heat Burst Develops

When a storm cloud starts to dissipate, lifts, and clears up, it leaves a layer of cold air behind. At this stage, most moisture has been removed from the air during rain showers or other forms of precipitation.

Due to gravity and disappearing updrafts, the dense air starts to sink to the ground. As it accelerates down, it gets subjected to increasing air pressure and friction.

The increased atmospheric pressure causes the air to warm adiabatically (similar to chinook of föhn winds down the slopes of a mountain). The friction between falling and stationary particles creates additional heat that contributes to the thermal buildup of the falling air.

Development Of A Heat Burst

The red arrows indicate the dispersing warm & dry winds of a heat burst below remnants of a dissipating storm cloud. Click on the image for a larger view.

The heated air also forces the remaining moisture to evaporate while momentum allows the layer of air to continue to speed to the ground. The result is a heated, dry pocket of air that hits the surface, forcing warm gusty wind to disperse away from this point of impact. 

To those readers familiar with a microburst, this process may sound similar to the formation of a microburst. There are some similarities, but also a few different characteristics that allow for the creation of a very different phenomenon.

These are among some of the defining characteristics of a heat burst that will be discussed in the next section.  

Characteristics Of A Heat Burst

For a heat burst to take place, a few conditions need to be in place. Some of them are not only characteristic of the phenomenon but also are what differentiate them from other weather events like microbursts. We look at them first.

1) High Elevation

A heat burst typically originates high in an anvil cloud (that is so synonymous with thunderstorms). It is due to the fact that the phenomenon occurs in the wake of dying thunderstorms, when clouds start to lift and dissipate, leaving a layer of cold air behind.

Anvil Cloud

It is this high altitude at which a heat burst forms, which allow it to travel further when it sinks to the ground. The greater distance enables it to be subjected to increased pressure and friction for an extended period, causing more heat to build up in the layer of falling air.

The lower altitude (combined with a higher moisture content) at which a microburst occurs, is part of the reason that the air reaching the ground remains cold and sometimes mixed with different types of precipitation.

2) Little Or No Moisture 

Another characteristic that is unique to a heat burst compared to similar events is the extremely dry air associated with this phenomenon.

By the time a heat burst starts forming, the storm system already dissipated, and most of the moisture lost due to heavy rainfall that occurred during the peak of the thunderstorm.

The little moisture that is left in the pocket of air evaporates in the warm air as it plummets to the ground. It is not uncommon to observe the phenomenon called virga (visible rain that evaporates before reaching the ground) beneath the cloud base where a heat burst occurs.

The opposite is true for a microburst. The high moisture content within a thundercloud allows this phenomenon to stay cold or even be cooled further as it descends to the surface.

3) Strong Winds

One of two main characteristics of a heat burst is the strong gusts of winds that it produces as the pocket of warm air hits the ground gets dispersed in multiple directions over the surface of the surface.

The height from which the layer of air falls, allows it to accelerate and reach high velocities before hitting the ground. Wind gusts can easily exceed 121 km/h (75 mph). For example, in May 1996, Oklahoma experienced a heat burst with wind gusts of up to 153 km/h (95 mph).

4) Sharp And Significant Temperature Rise

Temperature Rise

The second and most defining main characteristic of a heat burst is the sudden and significant rise in temperature at the surface. This sudden rise in temperature can last anything from a few minutes to a couple of hours.

In most cases, the rise in temperature occurs in a short amount of time. The temperature increase is also significant. It is capable of increasing the current atmospheric warm air by as much as 10° Celsius (50° Fahrenheit) or more.

Extreme examples include Almeria (Spain) in July 2019. Temperatures jumped from 28° Celsius (82° Fahrenheit) to an incredible 41° Celsius (106° Fahrenheit) in just 30 minutes. 

In July 2016, Oklahoma also experienced a similar heat burst when the temperature rose from 27° Celsius (80° Fahrenheit) to 41° Celsius (106° Fahrenheit).

Conclusion

What became clear throughout this post, is that a heat burst may not be such a well-known weather event, but one that will definitely be noticed if ever experienced. It has a dramatic effect over a short period, as the few examples in the last section illustrated. 

It should not be confused with a heatwave, though, which can last for days or months and also have a significant impact on weather and climate of any region it impacts.

This post aimed to illustrate what a heat burst is, how it develops, as well as highlighting the characteristics that define it. If the phenomenon were unknown or unclear to you, you would now be able to understand it, as well as the mechanisms that underlie it, entirely.

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!

Wessel


What Are The Doldrums? The Intertropical Convergence Zone Explained

What Are The Doldrums-The Intertropical Convergence Zone Explained

Many of you might have heard the saying, "down in the doldrums," usually meaning someone is depressed or lacking energy. But this term actually has its roots in meteorology and dates quite far back.

In truth, it dates back as far as the mid 19th century when this nautical term originated with sailors of the time when they used it to describe their predicament when their ships came to a stop and were unable to make any progress for days or even weeks on end.

This article explores what precisely the doldrums are, how it occurs, and look at some of its main characteristics.

What Are The Doldrums?

During the introduction, you already got a glimpse of what the doldrums are, but the description is vague and needs a more thorough and precise explanation. Before delving into the details, though, it is important to define the term first to lay the foundation:

What Are The Doldrums?

Sailing Boat

The doldrums is a term that refers to the Intertropical Convergence Zone, a calm and windless region close to the Equator where the northeastern and southeastern trade winds come together and clash.

It is an old nautical term used by sailors during the 19th century to refer to this part of the ocean when their sailing ships got stuck and were unable to make much progress due to the lack of wind.

It is clear from the definition that the doldrums is a location (the Intertropical Convergence Zone), and not a situation as the introduction implied. It may sound a bit confusing, but as you will soon learn, this is simply a result of miscommunication during the 19th Century.

As you can imagine, there were no radio or any other modern form of direct communication during this period. As a result, communication between ships and their headquarters thousands of miles away had to be relayed via written word or simple "word of mouth."

As a result, when reports reached officials on the mainland, describing the conditions they experienced as being "in the doldrums", it were misinterpreted as the sailors describing an actual location called the doldrums.

Without the misunderstanding corrected, a president was set, and the rest, as they say, is history. Today, the Intertropical Convergence Zone (ITCZ) still commonly gets referred to as the doldrums.   

How The Intertropical Convergence Zone Is Formed

As mentioned in the description, the Intertropical Convergence Zone (ITCZ), develops where the northeastern and southeastern trade winds meet at the thermal equator. (The thermal equator is not a fixed position on the planet's surface, but more on that in the next section.)

The ITCZ moves with the thermal equator as it shifts around 5 degrees north and south of the physical equator throughout the year. (For easier reading, the Intertropical Convergence Zone will be referred to as the ITCZ or doldrums for the remainder of this article.)

Formation Of The Intertropical Convergence Zone

The formation of a high-pressure system in the ITCZ. Click on the image for a larger view. 

The sun heats the surface of the land and sea at the thermal equator, causing it to warm the air directly above the surface. As the air warms and expands, it starts to rise, creating an area of low pressure at the surface. (Learn more about low-pressure systems in this article.)

The southern and northeastern trade winds approach each other and converge at the thermal equator. As they encounter the low-pressure system and rising air in the region, these stop moving in a horizontal direction and starts to move vertically with the rising air.  

As a result, there is almost no horizontal air movement remaining at the surface, and the little wind present is highly erratic. It is these windless conditions that form the ITCZ, more commonly described as the doldrums by the mariners of the 19th century.  

This band of low-pressure and relatively windless conditions, called the ITCZ or doldrums, encircle the entire planet and follow the thermal equator as it meanders to the north and south throughout the year.

Features Of The Intertropical Convergence Zone

With a clear understanding of how the ITCZ or doldrums develops, it is also beneficial to be aware of the different characteristics that this weather phenomenon display. The most notable of these have already been touched on but needs to be explained in more detail:

  1. Shifting Position
  2. Low-Pressure System
  3. Large Amounts Of Humidity And Rainfall
  4. Very Little And Erratic Air Movement

By looking at each characteristic individually, it will be easier to understand and see how it fits into the larger mechanism that drives the ITCZ.

1) Shifting Position

Throughout the year, the ITCZ moves with the thermal equator as it shifts around 5 degrees north and south of the geographical equator. This movement is closely related to the seasonal movement of the sun.

ITCZ Seasonal Shift

As a result, the ITCZ moves north during the summer months in the Northern Hemisphere and reaches its furthest point during July/August. It then returns south and crosses into the Southern Hemisphere, reaching its most southern position around January/February.

This is a very general description of the movement of the ITCZ. Its actual motion is more complex, and its position can shift unexpectedly over some regions. It can also remain over an area or stay away from it for extended periods with potentially devastating results.

Another variable that influences the movement of the ITCZ is the fact that the ground surface warms up more quickly than the ocean's water when exposed to solar radiation. It results in the ITCZ extending further over land than the sea at the same latitude.

Countries within the Tropics rely on the rainfall that occurs with the arrival of the ITCZ, which means that they can be severely affected by an unnaturally long stay or absence.

During a prolonged absence, a region may experience severe drought, depending on the length of time the ITCZ stays away. When this occurrence remains over an area for an abnormally long period, however, the large amount of rain can lead to widespread flooding.

2) Low-Pressure System

Although this post already briefly mentioned the development of a low-pressure system, it needs a more elaborate explanation to understand its importance.

The planet's surface at the Tropics receives more direct and intense solar radiation from the sun than any other part of the world. As a result, both the ocean and land surface gets extensively warmed up.  

In turn, the surface heats the air directly above it. As the air gets warmer, it expands and becomes less dense than the surrounding cold air. This leads to the lighter layer of air to start to rise, which leaves an area of intense low pressure near the ground. 

The importance of this powerful low-pressure system can not be emphasized enough. It is this weather condition that forces the air from the approaching trade winds to be sucked up in the strong vertical lift, which disrupts its horizontal movement.

3) Large Amounts Of Humidity And Rainfall

If you look at a satellite image of the Earth, the ITCZ can easily be identified by the band of clouds encircling the planet near the Equator. It represents the high humidity that forms the numerous rainclouds and thunderstorms occurring in this part of the world.

Heavy Rainfall

The high temperatures at the surface in the Tropics, combined with an abundance of water sources, leads the air to be saturated with moisture. As the moist air starts to rise and gain altitude until it reaches dew point, and condensation takes place.

The resulting stormclouds that form contain a large volume of water droplets. When it can no longer carry them, a burst of intensive and heavy rainfall follows. Although the rain does not last long, a large amount of water gets released in a very short period of time.

It is these short, intense rain showers that are so typical of the weather produced in the Intertropical Convergence Zone.

4) Very Little And Erratic Air Movement

It has been mentioned numerous times throughout this article, but as it is the primary reason for this article and the reason the term doldrums exist, it is worth noting again.

The most well-known characteristic of ITCZ is the absence of wind or very little and erratic air movement. The reason for this phenomenon has already been thoroughly explained.

It is also important to note that even modern sailing boats, no matter how technologically advanced, still battle to make progress and attempt to avoid getting caught in the clutches of this windless region at any cost. 

Conclusion

Even though the saying, "in the doldrums" may become a bit outdated, it is still used across the world without knowing the real origin of the term.

By now, there should be no confusion or doubt as to where the term, the doldrums, originated. Whether you want to refer to it as the doldrums or the Intertropical Convergence Zone, the dangerous windless conditions that define them, remain ever-present.

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!

Wessel



What Is A Derecho And How Does It Develop?

What Is A Derecho

We are so used to the characteristics of well-known storm systems like hurricanes, tornadoes, and heavy thunderstorms, that it's easy to mistake a lesser-known destructive storm as a more familiar one.

Occasionally though, the extreme weather you are experiencing may be part of something much bigger and more destructive. Since it exhibits the same characteristics as a weather event you are familiar with, it is easy to dismiss it as just that.

But what if the weather phenomenon you are experiencing, has a bow-shaped line of winds at least 400 kilometers (250 miles) wide, accompanied by strong gusts that can reach 121 km/h (75 mph) or more. Also, this long-lived system can easily travel more than 600 miles.

The weather phenomenon that is the focus of this article is precisely one such storm. It is called a derecho. From the figures you saw in the previous paragraph, it should be clear that this is an enormous event with potentially widespread and devastating consequences. 

This article examines what a derecho is and how it develops. It also looks at the widespread effect on humans and the environment.

What Is A Derecho?

From the introduction alone, it will become self-evident that a derecho is a very large weather event that affects a vast area. Before examining how this phenomenon develops, it is essential to have a clear definition of what precisely a derecho is:

What Is A Derecho?

What Is A Derecho

A derecho is a large-scale weather event that is characterized by a powerful bow-shaped line of wind storms that is driven forward by a series of severe thunderstorm systems.

These widespread and fast-moving winds extend over several hundred miles and last for an extended duration. They often result in the formation of tornadoes, hail, & flooding, and can cause widespread damage and destruction.

The name, Derecho, is derived from Spanish, which literally means "straight in English. It is highly appropriate since the winds that characterize this storm system travels in a long straight (with a slight bow-like curve).

For a weather event to be classified as a derecho, winds must reach sustained speeds of at least 93 km/h (58 mph), and the area affected by wind damage is at least 400 kilometers (250 miles) wide. Occasional wind gusts of at least 121 km/h (75 mph) must also occur.

Visually, an approaching derecho is often characterized by a bank of heavy shelf clouds (also known as an arcus clouds), which are synonymous with this extreme weather event. These clouds have a distinct shape that is as awe-inspiring as it is ominous.

How A Derecho Develops

One of the most critical components and main driving forces of a derecho is an extensive grouping of a series of thunderstorms traveling in the same direction. 

However, there are specific factors, both inside and outside these thunderstorms, that trigger and causes a derecho to form and grow into the widespread and devastating weather event we know:

Downbursts

The strong winds that are so characteristic of a derecho are produced through multiple occurrences of a process called a downburst within thunderclouds.

How A Derecho Is Formed

Early stages in the development of a derecho. Click on image for a larger view.

A downburst is a column of cold air that develops in the upper regions of a thundercloud. It starts to sink and accelerate to the ground. When the air hits the ground, strong winds get dispersed in multiple directions.

(Downbursts can further be divided into microbursts and macrobursts. You can find out more about microbursts in this article.)

Under the right conditions, a thunderstorm can generate multiple downbursts repeatedly within a specific region with a size of up to 100 kilometers (62 miles). The downburst clusters that occur as a result favor the creation of a derecho.

Prevailing Winds

Probably the most critical element responsible for a group of thunderstorms to start moving in a specific direction is the presence of prevailing winds. Without a consistent driving force to move storm systems unidirectionally, a derecho will not be able to form.

The influence of these winds can be observed from the moment a downburst of cold air hits the ground. The air diverges typically in all directions away from the point of contact. An overarching directional wind, however, causes a momentum shift in a specific direction.

When prevailing winds are present, the air diverging away from a downburst accelerates faster in the direction the surrounding wind is blowing. As a result, the momentum and forward movement of the storm system follow the direction of the prevailing wind.

Creation Of New Thunderstorms And Bow Echos

Usually, downbursts signals then end of the thunderstorms in which they are occurring. Due to prevailing winds, though, the pool of cold air that spreads faster in the general direction of the surrounding air cuts underneath the lighter warm in front of it, forcing it to rise.

New Thunderstorm And Pool Of Cold Air

New thunderstorm and pool of cold air reinforce Derecho. Click on image for a larger view.

The warm humid air that has been lifted by the cold winds ahead of the storm front, starts to cool down, and condensation takes place, which can result in the formation of an entirely new thunderstorm.

As the newly formed storm matures, another column of cold air develops and eventually drops to the ground. As a result, the pool of cold behind it already present from previous storms get reinforced by fresh downbursts from the new thunderstorm.

It becomes clear how this process can keep on repeating itself under the right conditions, gain momentum, and grow in size and strength. Under these conditions, the bow-shaped storm front that is so synonymous with Derechos, called a bow echo, develops.

This repetitive process is what makes it possible for Derechos to travel for hundreds of miles and cause so much destruction over such a widespread area.

At the leading edge of the storm front, distinctive-looking clouds called shelf clouds (also known as arcus clouds) form, which is as spectacular as they are ominous looking. They are as synonymous with Derechos as the bow echos these storm systems produce.

Characteristics And Effects Of Derechos

The effect a derecho has on any region it impacts is comparable to a large percentage of other extreme weather events like tornadoes and hurricanes. It is therefore not surprising that this storm system often gets confused with another weather event.

There are two characteristics of a derecho, though, that sets it apart from other storms and makes it so unpredictable and dangerous...

Surprise Element Of A Derecho

With most extreme weather events, there are some identifiable buildup or accompanying weather conditions that give meteorologists a fair amount of time to provide potentially affected regions with weather alerts of an approaching storm system.

Hurricanes can be tracked from their origins over the warm waters of the Subtropics and their path calculated with forecasting models. The buildup of supercells that have a high probability of tornadoes occurring can also be identified with Doppler radar systems.

Radar Image Of Derecho

Radar image showing the development and scope of bow echos that are so synonymous with a derecho. 

Although Derechos are widely recognized today and weather conditions conducive to their formation identified, they remain unpredictable and can seem to strike out of nowhere.

Hurricane strength winds, sometimes followed by a downpour of rain, can catch an entire region completely off-guard and hit without any visible warning. Although it moves through an area fairly rapidly, it can cause widespread damage and injuries in a short period.

It is this "surprise element" that is so characteristic of a derecho, that makes it so dangerous and potentially deadly.  

(Even experienced meteorologists can identify the conditions favorable for a derecho to form and signal a weather alert, but won't know for sure until it actually happens. It is part of what makes predicting this type of storm so tricky.)

Sheer Size And Scope Of Affected Regions

The second characteristic that sets a derecho apart from other storms is the sheer size of the area affected. As prevailing winds move a grouping of a thunderstorm in the same direction and form a singular weather event, it has a widespread effect.

The fact that a weather event needs to be at least 400 kilometers (250 miles) wide to be classified as a derecho, already points to the scale of the storm. In many cases, Derechos far exceed this minimum requirement.

Under favorable conditions, this storm system can also build momentum and travel for hundreds of miles. The damage on this scale, can not only be measured in injuries or loss of life but overall costs as well, which can run into hundreds of millions of dollars.

(The derecho that occurred during June 2012 in the Mid-Atlantic and Midwest of the United States, resulted in damage estimated to be in excess of 2.9 billion dollars.)

Wind Damage And Flash Flooding

The majority of destruction and injury caused by Derechos is the result of powerful winds and flash flooding that occur during the storm.

Widespread Destruction Of Trees By Derecho

Widespread destruction of trees by a Derecho weather event.

The sudden arrival of strong winds without any (or little) warning can cause severe damage to any region. Trees, power lines, and lamp posts, etc. can be completely flattened and structures severely damaged with winds reaching speeds of up to 160 km/h (100 mph.)

When enough moisture is present in a group of thunderstorms, and it moves slow enough over an area, flash flooding can occur. A region's topography with steep slopes and valleys can also result in the quick buildup of water, which can also trigger flash floods.  

Apart from the damage to structures and the environment, people caught outside or in nature carry the highest risk of getting injured or worse. The majority of fatalities caused by Derechos is as a result of people being struck by fallen trees/objects or drowning.

The widespread downing of power lines can also result in the loss of power to millions of homes and have a substantial impact on the region's economy. (The derecho of June 2012, mentioned earlier, caused a power outage to 4.2 million users over multiple states.)

Conclusion

What is clear from this article is that even though most people are not aware of its existence, a derecho is a powerful and widespread storm system. (Even though there is still a debate among meteorologists around the specifics of this phenomenon.)

The argument can be made that a derecho is just the sum of thunderstorms working in unison under the right conditions. But the same can be said about a thunderstorm or tornado that is also the result of individual mechanisms operating in the right environment.

This article explained what a derecho is and how it forms. It also looked at its characteristics and some of the most significant impacts it has on human life and the environment.

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!

Wessel


What Is A Microburst, And How Is It Caused?

What Is A Microburst - And How It Is Caused

At any point, while being outside, you might have experienced a sudden and unexpected downpour of rain, accompanied by extreme gusts of winds. You may just have encountered a microburst.  

A microburst usually occurs during a thunderstorm or heavy rain shower and often is relatively short-lived. It also dissipates as quickly as it arrived.

Wind speeds can reach up to 160 km/h (100 mph) as the air hits the ground and disperse. As a result, this phenomenon often gets confused for a tornado or hurricane.

This post examines what a microburst is, how it develops, and also looks at the different types of microbursts.

What Is A Microburst?

Meteorologist Ted Fujita was responsible for labeling the term microburst. He defined it as a downburst that occurs over a small area that affects a region with a diameter of no more than 4 kilometers (2.5 miles.) in size.

(He was also responsible for the term, macroburst, to identify downbursts larger than 4 kilometers (2.5 miles.))

Although a microburst displays many of the characteristics of a tornado (and sometimes a hurricane), it is a completely different type of meteorological event. Before examining how it develops in more detail, one needs to define what precisely a microburst is:

What Is A Microburst?

What Is A Microburst

A microburst is a localized and powerful downdraft created by a column of sinking air through the base of a storm or rain cloud.

The phenomenon can be divided into dry and wet microbursts, both of which can cause severe damage to the surface and objects in their path.

A cumulonimbus cloud, in which a thunderstorm usually occurs, can reach heights of up to 16 000 meters (52 000 feet). It is at these high altitudes where the cold air develops that form the basis for a microburst.

One more characteristic that makes it so difficult for meteorologists to forecast is the speed at which a microburst develops and also dissipates. This is also what makes it so unpredictable and dangerous.

How A Microburst Develops

With a clear understanding of what a microburst is, it is important to know how it develops. It will not only help to create a clear understanding of how and why it occurs but also why it displays the characteristics that are so unique to this phenomenon.

Development Of A Microburst

Development and execution of a typical microburst. Click on the image for a larger view. 

A microburst initially starts to form in the top part of a storm cloud, where pockets of cold and moist air accumulate and continue to build up. Two main factors trigger and contribute to a column of cold air to start dropping and accelerates to the ground:

  1. Precipitation Loading
  2. Evaporation Cooling

Sometimes, precipitation loading on its own can initiate a microburst, but it usually is a combination of both, working together to create a downburst with potentially devastating effects. A closer examination of each will show how they contribute to the occurrence.

1) Precipitation Loading

Precipitation loading is the raindrops, hail, ice crystal, graupel, and other forms of water that accumulate in the upper regions of a storm cloud. It gets carried up and kept airborne by the strong updrafts that occur within a large storm system.

Water carries a lot of weight, and when updrafts are no longer able to keep it in the air, it starts to drop to the ground. Sometimes it is the sheer weight of the moisture, combined with a dissipating storm system and weakening updrafts that trigger the event.

2) Evaporation Cooling

In the upper troposphere, external cold, dry air also comes in contact with the moist air in the cloud. It causes the moisture to start evaporating. Since evaporation is a cooling process, the air in the cloud begins to cool down.

The resulting pocket of cold air is much denser and heavier than the surrounding warmer air. As a result, this column of cold heavy air will start to sink to the ground.

When the sinking air exists the cloud base, it comes in contact with more dry air. Here, evaporation continues to take place, which cools the air down even further. As a result, the cold air drops even faster and accelerates towards the ground.


The actual occurrence of a microburst can be broken down into three primary stages:

  1. Contact Stage
  2. Outburst Stage
  3. Cushion Stage

By looking at each of these three stages individually, it will be easier to understand the complete process through which a microburst develops:

1) Contact Stage

Downburst Stage of a microburst

Microburst existing the cloud base before making contact with the ground.

During the initial stage of a microburst, cold air (often accompanied by raindrops) exists the cloud base and continues to accelerate to the ground.

The downdraft rushes towards and hits the ground at what is called the contact point (also called the splashdown point), from where strong winds diverge outwards. 

(For clarity, you can use the image of a water-filled balloon, dropped from a height and bursting open when it hits the ground with water being dispersed in all directions. The contact stage of a microburst closely resembles this image.)

2) Outburst Stage

The name of this stage itself is quite self-explanatory. During this stage, powerful winds get dispersed away from the splashdown point after contact with the ground.

These winds travel along the surface and can reach speeds of up to 160 km/h (100 mph) or more, powerful enough to cause severe damage to the environment and structures. Winds of this speed can flatten large trees and seriously damage large structures.

Depending on the type of microburst, the winds can be accompanied by heavy rain, which can add to the damage caused and pose additional dangers as well.

3) Cushioning Stage

In the final stages of the event, a layer of cold air forms at the surface where the downdraft first made contact with the ground. This cold air accumulated from the start of the microburst and build up as it progressed.

While the air, already at the surface and outer limits of the affected area, continues to blow strongly, the "cushion" provided by the layer of cold air below the downdraft prohibits any more air from reaching the ground.  

This final stage marks the start of the end of a microburst, which will blow itself out shortly after no more wind from the downdraft can reach the ground. The duration of a microburst can last anything from a few seconds to a couple of minutes.

Types Of Microbursts

As I briefly touched on in the summary of what a microburst is, there are mainly two forms of this event:

1) Dry Microburst

A dry microburst occurs when no rain is present in the column of air reaching the ground. It happens when there is very little moisture present in the cloud, and the cloud base is situated at a relatively high altitude.

The little rain that emerges from the cloud base with the downdraft quickly evaporates in the dry air below the cloud before it can reach the ground (also known as virga). As a result, it is only the dry air that reaches the round and gets dispersed in multiple directions.

2) Wet Microburst

A wet microburst occurs when a combination of heavy rain and wind reaches and gets dispersed over the ground. This happens where there is a high percentage of moisture present in a cloud.

Wet Microburst

A wet microburst occurring over Phoenix.

When the combined weight of the different sources of moisture in the top part of the cloud becomes too heavy, it starts to sink. As it drops through the cloud, it drags the surrounding air down with it, which accelerates the speed of the sinking column of air.

Subsequently, a combination of rain and wind is caught in the column of air that crashes into the ground, and both get propelled outwards with potentially devastating results.

Conclusion

They may not be as well-known as tornadoes and hurricanes as extreme weather events, but microbursts are just as severe and destructive. It should be very clear to you after reading this post.

This article also illustrated that, even though many of the characteristics are the same as a tornado, a microburst is an entirely separate weather phenomenon that is formed and develops through very different mechanisms.

After reading this article, you will know exactly what a microburst is, how it is formed, and what mechanisms are at work in the process.

Feel free to leave me any comments, questions, or suggestions, and I will get back to you 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!

Wessel


What Is A Mirage, And How Does It Occur?

What Is A Mirage And How Does It Occur

We have all seen a movie or cartoon where a thirsty wanderer in the desert spots an "oasis with water and trees at a distance," only to find nothing but sand when they reach its location.

This phenomenon can also be seen when you travel on a long stretch of road on a hot day, and you spot a large puddle of water at a distance. As you approach it, it continues to move further away.

Your eyes are not playing tricks on you, and you are not hallucinating. What you experience is nothing more than an optical distortion called a mirage.

In this article we explore what precisely a mirage is, how it is formed, and also look at the different types of mirages.

What Is A Mirage?

A mirage needs a combination of different variables to be in place for this phenomenon to take shape. Before we delve into a thorough explanation, it is important to have a short description to summarize what a mirage is:

What Is A Mirage?

What Is A Mirage

A mirage is an optical distortion that occurs naturally due to the refraction of light rays that creates a deceptive appearance of a distant object.

It usually occurs on a hot day where the temperature of the surface and air directly above it is much warmer than the air higher up in the atmosphere.

It is a simplified and concise summary of an event that needs a more detailed explanation to understand how it occurs and what mechanisms are at play during the process.

How Is A Mirage Formed?

The word mirage was directly borrowed from the french verb, mirer, which originated from the Latin word, mirari, which translates to "mirror" or "to look at." As you will shortly learn, this is quite an accurate description of the phenomenon.

Mirages can be divided into two types of optical distortions:

  1. Inferior Mirage
  2. Superior Mirage

By looking at them individually, it will soon become clear how each phenomenon is formed and why we see (or perceive) the resulting image in the way we do.

Inferior Mirage

The most familiar and commonly occurring form of this optical distortion is the inferior mirage. It can be seen on a hot day while traveling on a long stretch of road, or in the desert where the phenomenon first gained wide recognition.

A mirage is capable of producing a misplaced image of an object due to the capability of light to refract (bend) in a medium with non-uniform uniform attributes.

It is widely assumed that light travels in a straight path, especially at a speed of 299 792 kilometers per second (186 282 miles per second). In the vacuum of space, it does indeed travel in a straight line.

When traveling through a medium like the atmosphere, the difference in air density at different altitudes allows light to bend. This is because light always follows the quickest path, not the shortest path.

The illustration below will clarify how and why light behaves in this fashion, and how it contributes to the creation of a mirage:

How A Mirage Is Formed

This illustration shows how an Inferior Mirage is formed. Click on the image for a larger view

By making use of the illustration above, it will be much easier to explain and understand how an inferior mirage gets formed.

On a hot day, the Sun rapidly warms up the Earth's surface, which in turn, heats the air directly above the ground. It creates a substantial difference in air temperature between the warm air near the surface, and the colder air above it.

A medium with non-uniform properties has now been created with cold air, which is optically more dense, situated above warm air, which is optically less dense. 

Since light always follows the quickest past, and warm air with less resistance is much faster to travel through, the light will bend towards the hot air close to the ground.

As the red line in the illustration illustration shows, light travels from objects higher up in the colder air to the warm air close the ground, before bending back towards the eyesight of the observer.

The position where the light is not refracted anymore but reflects up towards the observer is called the point of total internal reflection. It is at this location where you will perceive the phenomenon to be located, when the actual object may, in fact, be hundreds of miles away.

Inferior Mirage

To simplify and make the description of a mirage easy to understand, an identical inverted image of the palm trees and water was used in the illustration. Although this is possible, more often than not, the objects in a mirage may appear to look like something it is not.

For example, the "water" you see may be nothing more than the blue sky reflected on the ground, and the palm trees may be a completely different object that got distorted as the light traveled through layers of hot and cold air. There may not even be a real object at all.

In summary:

  • An inferior mirage appears as a result of light bending towards warm air close to the ground, as the red line indicates.
  • It is possible since light follows the quickest (not shortest) path, which, in this case, is the warmer air near the ground, which provides less optical resistance.
  • The observer sees the distorted image much closer than it really is since the image is viewed via a direct line of sight by the observer, as indicated by the blue line.

The mirage is an optical distortion, meaning the image you see may be a distorted view of an actual object much further away. It can also show distortions that are not even part of the real object (e.g., the sky). It may even display items that don't even exist.

Superior Mirage

A superior mirage operates on precisely the same principles as an inferior mirage but has the exact opposite effect. Instead of showing an object much closer than it is, it displays an image of a distant object (that may be entirely out of view) on or above the horizon.

This type of mirage is a result of cold air that is trapped underneath a layer of warm air. This phenomenon is called temperature inversion (which you can read more about in this article.) As a result, light bends up, instead of down, towards the warmer air.

The illustration below will help to describe how a superior mirage gets formed:

How A Superior Mirage Is Formed

By making use of the illustration above, it will be easier to explain and understand how an superior mirage gets formed.

A superior mirage mostly occurs over the colder waters of the ocean or at the Arctic. The cold surface of the water or ice cools down the air directly above it, with a layer of warmer air lying on top of it.

In the case of this phenomenon, the light gets refracted up towards the warmer air, where it can travel faster before getting reflected back down towards the sight of the observer, as indicated by the red line in the illustration.

As a result, the observer perceives the object to hover above his/her eyesight and the horizon, as indicated by the blue line in the illustration. This occurrence is called looming.

Superior Mirage

Sometimes, you can observe this phenomenon while standing on the shoreline and watch a boat on the horizon, which seems to float in the air some distance above the water.

Superior mirages also occur when objects too far away to see due to their distance and curvature of the planet, "appears" above the horizon. This is possible due to the bending of light up towards the warmer air, and back down to the observer far away.

In summary:

  • A superior mirage appears as a result of light bending up towards warmer air situated above colder air near the surface, as the red line indicates.
  • It is possible since light follows the quickest (not shortest) path, which, in this case, is the warmer air higher in the atmosphere, which provides less optical resistance.
  • The observer sees the distorted image "floating" above the horizon since the image is viewed via a direct line of sight, as indicated by the blue line.

Conclusion

As you just learned, a mirage is not your eyes playing tricks on you. It is a real distorted image you see as a result of the refraction (bending) and reflecting of light. It is your brain that is programmed to interpret that what you see is something completely different. 

Often, it is the image of an actual object at a distant location, sometimes it is a distorted image that appears as something completely different, and sometimes there is no real object at all. 

Through this post, you learned what a mirage is, what the different types of mirages are, and how each one develops.

Feel free to leave me any comments, questions, or suggestions, and I will get back to you 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!

Wessel


Fujiwhara Effect: When Two Hurricanes Meet

Fujiwhara-Effect - When Two Hurricanes Meet

If you are a regular viewer of weather forecasts, there might have been the odd occasion when you noticed two large tropical storms in close proximity on the same meteorological map.

If you ever thought what might happen if these two massive storm systems came to close to each other, you are not alone. This very question has been on the minds of many observers, and not only studied by the meteorological community.

It also turned out to be a very valid question, since tropical storms that come close enough to each other do start interacting and influencing each other. This phenomenon is called the Fujiwhara Effect.

In this article, we will examine what the Fujiwhara Effect is, how it develops, as well the different potential outcomes that can occur when two storm systems approach each other.

What Is The Fujiwhara Effect?

Before we get into the details, we first need to have a concise idea of what exactly the Fujiwhara Effect is:

What Is The Fujiwhara Effect?

Fujiwhara Effect

The Fujiwhara Effect occurs when two Tropical Cyclones that rotate in the same direction come in close enough proximity to each other for their centers to start interacting and close the distance between them.

For this occurrence to take place, the distance between the two tropical cyclones must be within 1 400 kilometers (870 miles). In this space, the centers of both storms start to rotate each other around a common point, while they get drawn to each other at the same time.  

The processes involved in the development and different outcomes as a result of the Fujiwhara Effect will be discussed later in this post. Before we get to that, however, we need to address and clarify some potentially confusing storm names to avoid confusion.

Difference Between Hurricanes, Typhoons, And Cyclones

People often get confused or think that hurricanes, cyclones, and typhoons are entirely different storm systems. It can be problematic when describing a phenomenon like the Fujiwhara Effect, and these names get interchangeably used while discussing the event.

They are, in fact, one and the same type of storm. Meteorologists use the umbrella term, Tropical Cyclone, to describe all three occurrences.

The only reason these storms have different names is because of there location. Hurricanes, cyclones, and typhoons are named according to the region in which they occur:

  • The storm is called a hurricane when it occurs in the central and eastern North Pacific, or the North Atlantic Ocean.
  • The storm is called a typhoon when it occurs in the Northwest Pacific region.
  • The storm is called a cyclone when it occurs in the Indian or South Pacific Ocean.

These locations and naming can vary, depending on each region's unique classification and naming system.

It is important, though, to remember that all three names refer to the same type of storm system. It means that the Fujiwhara Effect refers to the interaction between the same two storms, whether they are called hurricanes, cyclones, or typhoons.

The Consequence Of The Fujiwhara Effect

Sakuhei Fujiwhara

Dr Sakuhei Fujiwhara

The Fujiwhara Effect is named after Japanese meteorologist, Dr. Sakuhei Fujiwhara, who first studied & identified the phenomenon in 1921. He was the first meteorologist to determine the tendency of two cyclonic storms to rotate each other around a common point.

Many factors influence the impact of the Fujiwhara Effect in different situations. We focus on the most important and common outcomes involving this phenomenon. Typically, three possible scenarios usually play out:

  1. Tropical cyclones of equal size and strength, collide and merge.
  2. Tropical cyclones of equal size and strength, collide and get diverted.
  3. Tropical cyclones with big differences in size, collide, and one gets absorbed. 

It will quickly become clear how these three different outcomes can occur when we look at each one in more detail:  

1) Tropical Cyclones Of Equal Size And Strength, Collide And Merge

As already mentioned, when two tropical cyclones are in close enough proximity, they start to interact and are drawn towards each other. If both these storms are of equal size, their centers continue to gravitate towards each other, as they also rotate each other.

(Due to the Coriolis Effect, the rotation is counterclockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere.)

When the two storm systems have closed the distance between them, the two centers (vortices) often merge to form a single storm.

More often than not, the merging of the storm centers has an additive effect. The result is a bigger and more powerful tropical cyclone, making it potentially more dangerous with increased destructive power and reach.

An example of this phenomenon occurred in 1994 when Tropical Storm Ruth interacted with Typhoon Pat in the Northwest Pacific. Their centers continued rotating closer to each other and eventually merged to form a single cyclonic storm system. 

2) Tropical Cyclones Of Equal Size & Strength, Collide And Get Diverted

Although tropical cyclones with the same size subjected to the same Fujiwhara Effect, often results in the merging and formation of a single cyclonic storm, this is not always the case.

Hurricanes Karina And Lowell

Sometimes, these storms rotate and attract each other for a certain period, before being deflected and shooting off in different directions. The significance of this result is that another storm system can dramatically change the projected path of a tropical cyclone.

An example of this outcome took place in 2014 when Hurricane Katrina, which traveled in a westerly direction, came into contact with Hurricane Lowell, which redirected it back to moving in an easterly direction.

3) Tropical Cyclones With Substantial Differences In Size Collide And One Gets Absorbed

Quite often, though, two cyclonic storms with significant differences in size are subjected to the Fujiwhara Effect. During such an occurrence, the smaller storm is drawn and starts to rotate the much bigger tropical cyclone.

Once the distance between the two storm systems has closed, the smaller tropical cyclone is overwhelmed and entirely absorbed by the strong vortex of the larger storm.

An example of this occurrence took place in 1993 when Tropical Storm Irwin got absorbed by the more powerful Hurricane Hilary. The same happened in 2005 when Hurricane Max collided with and completely absorbed Tropical Storm Lidia.

Conclusion

Although the Fujiwhara Effect does not occur that often and are not well-known, this post clearly illustrated the significant impact it can have when two cyclonic vortices, spinning in the same direction, start to interact with each other.

This article explained what the Fujiwhara Effect is, how it develops, and the different potential outcomes that can occur as a result of this phenomenon.

Feel free to leave me any comments, questions, or suggestions, and I will get back to you 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!

Wessel

How Do Hurricanes Get Their Names? And Why Were Women Singled Out?

How Do Hurricanes Get Their Names

There is probably not a single human being on the planet with access to information who does not know what a hurricane is. (Or cyclone in the Southern Hemisphere.) They are so powerful and destructive that they even get their own names.

Especially in the United States, you don't have to think too hard to remember hurricanes that were especially devastating in recent times. Names like Katrina, Harvey, and Sandy immediately springs to mind. And these just occurred during the early part of this century.

This leads us to the question as to why these storm systems get named after humans, and more specifically, given female names up till recently.

The answer to both questions is quite logical and makes sense if you look at the reasoning behind the decision to give them human names. To make sense of it all, we will need to go back in time and take a quick history lesson.

Why Are Hurricanes Named After Females?

It will be best to address the elephant in the room first. Especially in today's politically correct times, there are most probably a considerable amount of women who don't appreciate the fact that a violent, destructive storm always used to get a female name.

Female Symbol

The practice of attributing female names to hurricanes was a common practice until recent times. Even today, although this is coincidental, some destructive hurricanes still have some female names attached to them. (Think of hurricanes Katrina and Sandy.)

The practice dates back centuries and is rooted in maritime customs. In ancient times, sailors used to dedicate ships to goddesses, and in recent centuries, seen as mother figures by ship's captains and mariners.

The image of a ship as a vessel protecting her cargo like a nurturing mother also played a role. As a result, it was common for captains and naval commanders to not only name their ships after a woman but also to refer them as "her" or "she."

Before 1950, hurricanes were named according to their latitude-longitude numbers, which turned out to be complicated and confusing for people to tell hurricanes apart. At some point, specifically, in the West Indies, these tropical storms were even named after saints.

Experts soon realized that using an actual person's name, made hurricanes easier to remember and less confusing to tell apart. After trying a system that used the phonetic alphabet to name storms in 1950, it was abandoned due to a fear of repetitive names.

In 1953 the National Weather Service adopted the practice of naming hurricanes after women, copying the method traditionally used by naval meteorologists, which roots we explained at the start of this section.

(The system was revised again in 1979 when male names were incorporated into the naming process. More on the adoption of the various systems in the next section.)

It only becomes clear when you look back in history, why female names were so closely connected with hurricanes and cyclones.
The fact that these storms always originate over the warm waters of the Subtropics, further explains the connection with maritime practices.

How Do Hurricanes Get Their Names?

Parts of the history that lead to the creation of the current system we use for naming hurricanes were already touched on in the previous section while explaining the use of female names to identify these storms.

A Short History Of Hurricane Naming

Hurricane

The best way to understand how the current naming system was shaped, is to look at the defining dates in history when different processes got introduced which lead to the internationally recognized procedure currently run by the World Meteorological Organization:

Pre 1900s

For centuries, prior to the 1900s, hurricanes were named after saints, specifically in regions surrounding the West Indies, as mentioned earlier in the post. Two noteworthy hurricanes are Hurricanes Santa Ana and San Felipe, both of which hit Puerto Rico in the 1800s.

Early 1900s

During the 1890s and early 1900s, an Australian meteorologist by the name of Clement Wragge was credited as the first individual to started using women's names to identify tropical cyclones.

(A tropical cyclone is the umbrella term used to describe all tropical storms, from a tropical depression to hurricanes and typhoons. If you want to find out more about the difference between the different types of tropical storms, you can get more information in this article.)

1950

The trend to use female names continued to grow, while the more confusing system of using "latitude-longitude numbers" to name hurricanes was still used, but more limited to scientific communities. 

The advantage of using easy-to-remember human names gained popularity. This lead to the United States National Hurricane Center adopting a formal naming system in 1950, based on the military's phonetic alphabet. (For example, Able, Baker, and Charlie.)

1953

The phonetic alphabet system was limited, though. It ran the risk of reusing some names in too short a period of time, so it was revised to avoid repetitive naming.

The revised system was introduced in 1953 and used female names in the Latin alphabet. The decision to use female names was based on the method used by naval meteorologists. In turn, they adopted the age-old habit of mariners to assign female names to objects.

1979

In 1979, this setup had another noteworthy revision with the inclusion of male names with those of females. The National Hurricane Center also doesn't control the naming system, but instead, the procedure is regulated by the World Meteorological Organization.

It is this procedure that is firmly controlled by the WMO, which is currently followed worldwide, which we will discuss in more detail in the next session.

The WMO Hurricane Naming System

Today, the World Meteorological Organization has strict control over the naming of hurricanes, that is adhered to by the vast majority of national weather services globally. 

WMO Hurricane Names List

The illustration above shows the full list of names allocated to hurricanes from 2019 - 2024. Click on the image for a larger view.

In a nutshell, the system consists of 6 lists of names, each containing 21 names in alphabetical order. One list is used each year, with the following list used the next. This procedure continues for six years until the whole process starts all over again.

Each list uses the Latin alphabet with both male and female names used in alphabetical order. Only 21 names are used, since the letters, Q, U, X, Y and Z are excluded for obvious reasons.

(Hurricanes occurring over the West Coast of the United States use 24 letters of the alphabet, sins only the letters Q and U get excluded.)

If more than 21 storms occur during a year, the Greek alphabet is used to add additional names to the list.

When merited, some hurricane names are permanently retired from the system. It happens when a storm is so severe that it caused widespread destruction and loss of life, making its reuse potentially sensitive. This decision gets made during the annual meeting of the WMO.


It is important to note that the system used for naming hurricanes discussed in this article is mainly applicable to the North American region. 

Other parts of the world, especially in the Southern Hemisphere, use their own systems. However, the majority of them use a variation of the model described in this post, utilizing a certain number of lists rotated every few years, and also use names in alphabetical order.

Conclusion

As you probably concluded from reading, the current system we use to name hurricanes is not just efficient and practical, but also easy to remember for the average observer.

Although the system has been updated and revised to include male names in 1971, it is clear from looking back through history how the connection between hurricanes and female names got established in the first place. 

The primary aim of this article was to explain the process through which hurricane names got chosen, where it originated from, and why they were given female names in the past.

Feel free to leave me any comments, questions, or suggestions, and I will get back to you 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!

Wessel


Advantages Of Global Warming – Is There An Upside To Climate Change?

Advantages Of Global Warming

We are all well aware of the potentially devastating effects of Global Warming and Climate Change. But does Global Warming have any significant advantages?

You can tell the meteorological and environmental effects attributed to global warming off the top of your head; Heat waves, flooding, polar vortexes, sea level rise, droughts and an increase in violent storms are just events that springs to mind.

With this flood of devastating events and predictions of a doomed future we are bombarded with on a daily basis, can there be any positive influences or advantages to global warming?

What Is Global Warming?

To describe what precisely Global Warming is and how it works, will take so long to explain, that it may merit a very long separate article, or fill up the pages of a novel-sized book. But before we can talk about its numerous effects, it needs to be defined in some way:

What Is Global Warming?

What Is Global Warming

Global Warming is the gradual and sustained rise of global temperature averages over the long term. It is mostly observed as a result, or in the light of human activity that is directly or indirectly responsible for warming the Earth's surface and atmosphere.

It is considered to be the main driving force of Climate Change, and the two terms are so closely linked that they often get interchangeably used when discussing the same phenomenon.

Needless to say, this is a broad and cryptic description of what is essentially a very complex phenomenon, with the numerous processes at work within it on a local and global scale.

I already touched on many aspects of global warming in other articles on this website, which you will be familiar with if you are a regular reader of posts published on this platform.

To get a better understanding of how global warming works, especially in light of human activity, you can read this article first, which focuses on the role of greenhouse gases in promoting the warming of the planet.

If you need more information on the different ways in which humans directly produce heat to accelerate the warming of the planet & atmosphere, you can read about it in this article.

Is Global Warming Real?

Before we delve into this question, let me make the following statement and put it in bold so that it is very clear, and there is no confusion.

The following is for the sake of climate skeptics or believers that Global Warming is a natural process where human activity plays an insignificant or no role at all. I am not interested in convincing anyone, no matter what your stance on the subject.

I only want to answer the question that was asked in the heading with proven facts. I am not interested in who or what is to blame or take any specific stance on the matter.

Global Warming Is Real

With that said, the answer to whether Global Warming is real is a resounding Yes. And this can be proven and backed-up by simply looking at the temperatures officially recorded throughout the world over several decades.

Official thermometer-based keeping of temperature records started around 1850. It offers us more than a century of data to prove that Global Warming is a stark reality. But there is more evidence than just temperature readings to further substantiate this reality. 

By merely looking at a few measurements and comparisons taken over time, it will soon become clear just how fast the planet's surface and atmosphere is warming up:

1) Global Temperature Rise

Over the past 150 years, global temperature rose by 1° Fahrenheit (0.9° Celsius.) It may sound like an insignificant change from a shortsighted human perspective.

But when you think of the timescale over which natural global climatic and geological changes take place, the whole picture changes dramatically.

If you take into consideration the fact that the Earth is 4.5 billion years old, and climate change normally occurs over hundreds of thousands of years, you will realize how significant and rapid this change is.

2) Rising Sea Levels

Over the last century alone, the sea level rose by around 7 inches (178 millimeters). Like temperature, it may not seem like that much to you if you don't look at it in context.

Take into consideration that the oceans cover 71 percent of the Earth's surface. If you think of the sheer magnitude and scale, you will start to realize just how much ice and snow have to melt to raise such a vast surface by 7 inches.

All this additional water is a result of the melting of ice. The polar ice caps, glaciers, and snowpacks that stayed in their solid form for thousands of years have started to melt due to the increasing rate in temperature rise.

3) Highest Carbon Dioxide Levels Ever

Currently, carbon dioxide levels are the highest they have been in 650 000 years. If you are not familiar with carbon dioxide, this may not seem that relevant.

Carbon Emissions

Carbon dioxide is a greenhouse gas, which means it is a form of gas that prevents heat from escaping the atmosphere, trapping the warm air near the planet's surface. (In part, CO₂ is the result of emissions created during the burning of fossil fuels like petroleum and coal.)

This process contributes to the buildup of heat in the atmosphere. And the higher the concentrations of CO₂ in the air, the larger the amount of warm air that gets trapped. 

If you want to find out more about carbon dioxide, you can read all about how it is created, and its effect on the environment in this article.

4) Shrinking Ice Sheets

Satellite data from NASA shows that the ice sheets in both Antarctica and Greenland have been losing ice at an alarming rate of 413 gigatons per year combined since 2002. (If you can wrap your head around it, that is 413 billion tons of ice...)

This dramatic reduction in size is a direct result of warmer air and ocean surface temperatures. What is even more distressing, is the rate at which the ice sheets are shrinking, have started to accelerate since 2009.


It should be clear by now that there is no doubt that Global Warming is real, with more than a century's worth of data to back it up. And it shows no signs of slowing down soon.

Advantages Of Global Warming

Many of the negative impacts of Global Warming has already been highlighted in this article. It leaves us with the question of whether there can be any positive effect or benefit to this ongoing phenomenon?

Over time, it is clear that most long-term disadvantages will outweigh and eventually eliminate any short-term advantages. 

For a limited period of time, however, some of the side-effects of a warming planet will benefit and create new opportunities for certain industries and sectors. It will even have some temporary health benefits:

1) Less Winter Related Illnesses

Countries that traditionally experienced very cold winters may show a decline in deaths related to persistent icy weather, as Global Warming continues to warm up the planet.

Cold weather is 20 times more fatal than warm weather. This theory is the brainchild of Antonio Gasparrini (London School of Hygiene and Tropical Medicine).

He proved his theory in a study where he examined 74 million deaths. From the total, 5.4 million fatalities were contributed to cold weather, while only 311 000 were related to warm weather.

Cold related deaths are more prominent in people with developing or weak immune systems such as children and the elderly. If you are interested, you can find more detail about the effect of cold and warm weather on human health in this article.

2) New Shipping Lanes

The Arctic is warming at twice the rate of the rest of the planet. It is a result of Arctic Amplification, a process you can read more about in this article.

New Shipping Lanes

Combined with warmer ocean surface and air temperature, it is causing the ice to melt at an increasing rate. One temporary advantage of the accelerated shrinking of the ice sheets is that parts of the region that were previously covered with ice are now open waters.

This is especially beneficial for the North Sea Shipping Lane. It runs through the Arctic and is a much faster (and more economical) path to carry oil from Norway and Russia to global markets. 

Currently, it is covered with ice for large parts of the year, making it inaccessible. As temperatures continue to rise, more ice will melt, and it may open the shipping lane for extended periods, and possibly on a permanent basis.

The rapid melting of ice can also open entirely new shipping lanes that are currently not even under consideration or seen as a possible crossing.

3) Growth In Certain Agricultural Sectors

Countries in the Northern Hemisphere (close to the Arctic Circle) that were covered with snow for large parts of the year with accompanying low temperatures are now presented with new opportunities in the agricultural sector. 

Warmer temperatures that lead to less snow have freed up more fertile ground and created favorable conditions for the growth of crops that were previously impossible in countries like Sweden, Denmark, Finland, and Canada.

It is estimated that Northern Europe can expect a 30 percent increase in the production of wheat, while Finland and Sweden may see a 50 percent increase in areas suitable for the growth of corn. (Canada and Greenland can see similar advantages.)

4) Increased Plankton Biomass

Plankton Biomass (phytoplankton) is at the bottom of the marine food chain, which feeds the smallest marine organisms. In turn, they provide nutrition for larger marine species.

Warmer temperatures will result in an increase in the production of plankton biomass since phytoplankton makes use of the sun's energy to turn carbon into protoplasm (living cells in a plasma membrane) through a process called photosynthesis.

With more nutrition available, higher levels of phytoplankton can lead to an increase in volume and biodiversity of marine life in the ocean. Depleted or endangered fish species may also be given a chance to recover, while their numbers can start to grow again.

Conclusion

There are a few crucial facts that got highlighted in this article. One is the clear evidence and reality of Global Warming. The second takeaway is that there are some short-term benefits to a warming planet, but they have to be seen in context.

The emphasis of these benefits is that they are all short-term. Some countries and industries are already seeing some of these advantages, while others will experience them in the near future if global temperatures continue to rise.

If the planet keeps on warming past the point of being a benefit, everyone will be negatively impacted, even those who experienced a temporary advantage.

Looking at Global Warming from a slightly different perspective helps one to understand the process and consequences of a warming planet even better, and what it means for humans and the environment in the future.  

Feel free to leave me any comments, questions, or suggestions, and I will get back to you 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!

Wessel

What Is The Water Cycle, And How Does It Work?

What Is The Water Cycle

The flow of water is all around us. It runs from reservoirs into the faucets of our homes, and it's the rain falling outside. It is in the rivers and clouds, and the ocean contains more than 90 percent of all water.

No matter where you find water, whether it be in a vast lake in the mountains or a cloud high in the troposphere, it is part of the global movement of water. 

Even in all its states, whether it be solid (ice), liquid (water), or gas (water vapor), it still forms part of this interconnected water movement.

All movement and every path that water follows on a local and global scale, are part of what is known as The Water Cycle.

This article will focus to explain what The Water Cycle is, how it works, and its importance for all life one Earth.

What Is The Water Cycle

The water cycle is a large and complex system with many moving parts that may seem to work in isolation, or are part of a global network. Before we can start to delve deeper into its workings, we need to provide a broad description of what precisely the water cycle is.

What Is The Water Cycle?

The Water Cycle

The Water Cycle is the movement or path of water in its various forms across the world, both on land, sea, and the atmosphere.

This includes all related physical processes such as precipitation, evaporation, condensation, and transpiration.

As you can see, it is a very broad description, and to really understand it, one will need to look at some of the more specific processes involved, both on a local and global scale. 

Before we look at the steps involved in the creation of more specific water cycles, one should first establish a clear picture of the primary water sources (where the movement of water originated from.)

Sources Of Water

It is impossible to pinpoint exactly where a specific water cycled started by merely looking at the current phase in which the cycle is observed. What makes it even harder is that it is a never-ending process with no current start or endpoint.

What is certain, however, is that all processes and cycles need a primary source of water. By looking at the major water sources and where they are situated, one will get a much better idea of where and how some water cycles are set in motion.

Sea Water

sea water

The world's oceans contain 97 percent of all water on Earth. This is saltwater, though, which makes it unsuitable for consumption in its natural form. But this does not disqualify it from being part of the water cycle.

Water can evaporate from the surface water, and since oceans cover 71 percent of the entire surface of the planet, it serves as an almost unlimited supply of moisture.

Fresh Water

Even though the ocean can provide fresh water indirectly (through processes we will discuss later in this post), it is not water that is available for immediate use. This leaves the planet with only 3 percent of fresh water, of which less than a third is readily available.

Polar Ice Caps

Of the 3 percent of freshwater on Earth, two-thirds are stored in the polar ice caps, and to a lesser extent glaciers, and snowpacks at high altitudes. The location and make-up of this solid form of water make it inaccessible for an extended period of time.

Dams, Rivers, And Reservoirs

Most of the remaining freshwater can be found in more traditional sources of freshwater we are familiar with, like dams, rivers, and reservoirs. They receive their water through precipitation, melting snowpacks, and smaller streams. 

Groundwater And Aquifers 

A small percentage of water infiltrates the ground, allowing groundwater to replenish and aquifers to fill. Some of these subsurface water sources find openings on the surface and escape into surface water. Others flow directly into the ocean through underground run-off.

How The Water Cycle Works

As mentioned earlier in this article, the water cycle as a whole is a complex mechanism with many smaller processes involved in the broader global movement of water. The best way to explain it is to look at some of these processes in isolation.

By using a relatively simple example of how the water cycle works and highlighting each critical process along the way, one will be able to get a clear understanding of how the process works as a whole.

As a starting point, water needs a primary source and mechanism to enable it to turn into its gaseous form, which will allow it to be transferred through the atmosphere. Two processes make this possible:

  1. Evaporation
  2. Transpiration
  3. Sublimation

Both of these processes fundamentally do the same thing. They allow water to be transformed into its gaseous state and escape into the atmosphere. The only difference is the source from where it turns into water vapor, and the process through it takes place.

Evaporation

Evaporation

Evaporation occurs when the surface of a body of water in its liquid form is turned into water vapor. Primary sources include the ocean, dams, rivers, lakes, and other water bodies with their surfaces exposed to the atmosphere.

Evaporation is made possible by an increase in temperature. Solar radiation is usually the primary source of heat as the sun warms up the water's surface. The molecules in heated water become more energized, allowing it to break free from the surface as water vapor.

Transpiration

Evaporation is not the only source of water vapor. Depending on density and composition, vegetation provides a significant amount of water to the atmosphere. It occurs through a process called transpiration, where water vapor forms from the moisture created on leaves.

The roots of a plant or tree draw water from the ground. The moisture is then transported through the branches or stems into the leaves. The micro water droplets exist the leaves through small pores on their underside. From there, it escapes into the air as water vapor.

Sublimation

Sublimation is the transformation water from its solid form (snow and ice) directly into water vapor without turning into a liquid first. This usually happens on high snow-covered mountaintops or other regions at altitude.

The heat from the sun is also responsible for this process, but since the process sometimes occurs in subzero temperatures, wind plays a big part, as it carries the small amounts of water molecules that evaporate away without leaving any liquid water behind.


Once in the atmosphere, water vapor gets subjected to a variety of variables that will determine how far and high it will travel, as well as where and in which form it will change its state back into a liquid or solid form.

Global wind movement can literally carry water vapor around the globe, but for the sake of this illustration, we will focus on a water cycle that is the result of local and prevailing winds.

Once water vapor enters the atmosphere, the water molecules start to rise up in the air due to the difference in pressure and the buoyant properties of the lighter vapor particles. (Water vapor molecules are lighter than the surrounding particles in the atmosphere.)

As it continues to gain altitude, the temperature continues to drop until the water vapor reaches dew point and condensation takes place.

Transportation

In this specific cycle, water vapor in the air gets carried towards the coast and inland by onshore winds. This horizontal movement of moisture is called transportation. A sea breeze is one example of the type of wind blowing inland from the ocean.

Condensation

Condensation

Condensation is the process through which water in its gaseous state (water vapor) gets turned back into its liquid (water) or solid (snow) form.

Both liquid and solid particles continue to grow in size until it becomes too heavy to stay in the atmosphere and fall to the ground in the form of precipitation.

Precipitation

Precipitation occurs when small water droplets or ice crystals grow and cling together. When they reach a certain size, they fall to the ground due to the Earth's gravity and the inability of wind flow in the atmosphere to maintain their buoyancy.  

When the temperature is above freezing point, precipitation is in the form of raindrops. In subzero temperatures, precipitation takes the form of snowfall, since the water vapor usually condensates directly into ice crystals (the solid form of water.) 


Very often, even the global transport of water starts at a local level. The relatively simple cycle of water vapor from the ocean that gets blown over land where precipitation takes place is one such case and serves as the perfect example to explain the water cycle.

Depending on where and in which form precipitation occurs, the water is captured and stored in different forms:

  1. Snowpacks
  2. Surface Water
  3. Groundwater

All these forms of water sources play a crucial part in the water cycle and the supply of fresh water throughout various locations on land.

1) Snowpacks

Snow and other forms of solid precipitation fall and accumulate in regions with subzero temperatures to form snowpacks. Even in areas where you usually don't experience snowfall, you often see the mountaintops capped with snow due to their high altitude.

Snowpacks are a valuable source of fresh water. When temperatures start to rise, the snow melts and flows from mountains and other elevated regions into streams and rivers where it can be captured and stored.

2) Surface Water

Surface Water

When rainfall occurs over land, it can fall directly into rivers, dams, and reservoirs. It can also fall on impermeable surfaces, where gravity will force it to flow via surface runoff areas into streams, rivers, and standing water bodies.

Sometimes the runoff areas direct the flow of water directly back into the ocean, or it may encounter soil or other porous surfaces where it gets absorbed as groundwater, which also serves an essential purpose.

3) Groundwater

A large percentage of water falls directly on land. If the surface it falls on is soil or a form of porous rock, the water gets absorbed and becomes groundwater. Below the surface, the moisture gets stored in aquifers.

The water table sits on top of the aquifer and serves as an indicator of the amount of water saturation in the ground. When the soil is fully saturated, the water table lies close to the surface. When the land is arid, it is situated far below the surface and may be unreachable.

Especially when saturated, very often, the groundwater does not stay in one place. It is absorbed by the roots of plants and trees, which is essential for their livelihood.

springs and geysers

When situated at a gradient, groundwater will continue to flow through the porous ground. Where it finds a weakness or opening, it sometimes escapes to the surface in the form of springs and geysers or escapes directly into existing bodies of water like rivers and dams.

Groundwater may not escape to the surface at all, but continue to flow in underground "rivers" where it will eventually return to the ocean.

All three forms of fresh water eventually find their way back to the ocean in some way, where the cycle starts all over again. And that is the water cycle in a nutshell.

Even in this fairly simplistic system we just discussed, there are variations and processes involved, with different outcomes that also play a part and have a significant influence on the larger cycle.

Variations In The Water Cycle

As just mentioned, the existing processes we highlighted throughout this post, can have a variety of different outcomes and influences, even within a relatively simple water cycle like the one we focused on in this article.

Here are just a few variations that may occur within this system:

  • Due to factors such as unexpected changes in wind movement, water that evaporates over the ocean can stay over the water, condensate and form precipitation. The precipitation occurs over the ocean and none of the moisture-filled air reaches land.
  • Similarly, water vapor can escape from inland water bodies, rise, and condensate over land. As a result, precipitation will occur over inland regions without ever reaching the ocean. A significant amount of water vapor stays in this cycle and not immediately return to the sea.
  • External weather systems can result in cold prevailing winds blowing over the ocean's water, preventing evaporation from occurring for sustained periods. As a result, areas close to the ocean can experience a water shortage, which can turn into drought conditions over time.
  • Finally, water evaporating from water sources on land can be carried back to the ocean as a result of off-shore winds, where condensation and rainfall take place over water. It will also put pressure on remaining water resources in regions affected by this loss of precipitation.

These are just a handful of scenarios that can occur within a localized system. There are numerous processes and patterns that can occur as a result of local and global influences. 

Conclusion

One clear conclusion that we can reach is that the water cycle is a very complex system that operates on a local and global scale. It is the result of the interaction between various weather systems and patterns that transforms and move water across the globe.

Although we used a relatively localized form of this cycle to explain how it works, it is clear to see that the water cycle doesn't operate in a vacuum. It was illustrated by showing some possible variations that may be the result of external or global weather behavior.

This post aimed to explain what the water cycle is and how it works, by describing a typical local process that can also apply to different and more globalized forms of this cycle.

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

If you like to be informed whenever a new article is released, and also receive helpful tips & information, you can stay updated by simply  following this link .

Until next time, keep your eye on the weather!

Wessel

What Is a Jet Stream, And How Are The Different Types Of Jet Streams Formed?

What Is a Jet Stream?

We are all familiar with local winds caused by temperature gradients, changes in topography, etc. What most of us are not even aware of, is the strong bands of winds occurring high up in the atmosphere.

We don't experience or see the direct impact of these powerful winds, but they are essential for the creation of weather systems across the world. They are so influential that one can go as far to state that a large number of major weather events cannot occur without them.

These winds are called jet streams and occur in specific regions at different heights around the globe. But what are these powerful winds, and how do they form?

In this post, we take a look at what a jet stream is and how it forms. We also examine its effect on weather systems.

What Is a Jet Stream?

Before we can examine how jet streams are formed, and look at their effect on the weather, we need to define what a jet stream is first:

What Is a Jet Stream?

What Is A Jet Stream?

Jet streams are narrow winding bands of high-velocity winds blowing from west to east in the upper troposphere (tropopause).

These permanent strong winds form as a result of the temperature difference between warm and cold air and circumvent the earth following a fairly straight or meandering path.

These phenomena are referred to as narrow bands (or ribbons) of wind since it is hundreds of kilometers in width, but only a few kilometers in depth.

Although relatively stable in their position, they can move more to the south or north, depending on the season, and influence the weather conditions below them during the process.

Types Of Jet Streams

The atmosphere contains two primary jet streams:

  1. Polar Front Jet
  2. Subtropical Jet

Both the Northern and Southern Hemisphere have a polar and subtropical jet stream, creating four permanent jet systems in total surround the Earth. Both types of jets are created by a difference in temperature between two air masses.

Smaller, temporary jet streams also exist. African Easterly and Somali Jets are two of the better-known ones. Other occurrences include barrier and valley exist jet streams. They are not nearly as influential as two primary systems, though, which will be our focus. 

How Are Jet Streams Formed?

Both Polar Front and Subtropical Jets are formed in the same manner. There are subtle differences, though, which is why the formation and characteristics and of each system will be examined separately to avoid any confusion. 

Polar And Subtropical Jet Stream

Formation of the Polar & Subtropical Jet Streams in the Northern Hemisphere

The Polar Front Jet Stream And How It Is Formed

The polar front jet stream occurs at 60 degrees north and south of the Equator at heights of 9 - 12 kilometers (30 000 - 39 000 feet) in the troposphere. The wind speeds can reach and exceed 321 km/h (200 mph).

The Northern Polar Jet sits above the polar front and is the result of the temperature difference between the cold arctic air and warm tropical air. As the two air masses meet, the difference in air pressure between them produces what is called a pressure gradient force.

(Air always flows from an area of high to an area of low pressure. The warm tropical air has a much higher air pressure than the cold air from the North and South Poles, hence the strong pressure gradient force.)

The Coriolis Effect

The Coriolis Effect, deflecting winds to the right in the Northern Hemisphere and to the left in the Southern Hemisphere

In the Northern Hemisphere, one would assume the strong pressure gradient will cause the warm tropical air to flow northwards towards cold air over the poles. However, The Coriolis Effect forces the air to be deflected to the right.

In the Southern Hemisphere, the deflection is towards the left. As a result, a polar jet is a strong wind which is created along the border between the two different air-pressure masses, flowing parallel to the pressure gradient from west to east.

The Southern Polar Jet has the same characteristics as its northern counterpart and is created in the same way. Unlike the Northern Polar Jet, though, it follows a fairly consistent clockwise path around the Antarctic and does not shift or meander as much.

Since Antarctica is also far removed from any other landmasses and populated regions, the amount of seasonal north-south shifting in the jet stream will have very little if any significant effect on any human or plant life, as well the environment.

The Subtropical Jet Stream And How It Is Formed

The subtropical jet stream occurs at 30 degrees north and south of the Equator. It is slightly weaker and forms at higher altitudes than the polar jet and can be found at heights of around 10 - 16 kilometers (33 000 - 52 000 feet.)

The subtropical jet in the Northern Hemisphere is also a result of a strong pressure gradient that is created by the temperature difference between the warm air from the tropical region and the colder mid-latitude air.

Due to the strong temperature gradient and the deviation to the right due to the Coriolis Effect, a strong band of wind flowing westward is created, The Subtropical Jet Stream.


Keep in mind that the formation of a jet stream involves complex processes, and the ones described here are simplified explanations to make these phenomena easier to understand. It still manages to capture the essence and accurately portray the basics of these systems.

How Does The Jet Stream Affect Weather?

To say that jet streams affect the weather is a mild understatement. They create and are the main driving forces of numerous major weather systems and seasonal weather change across the world.

To name every possible event and occurrence that is either directly created or influenced by these powerful upper-atmospheric winds would be impossible, and take up a whole encyclopedia. We will focus on the most important ways in which jet streams affect weather.

Polar Jet Stream and Rossby Waves

Chicago in an icy grip as Rossby waves in the Polar Jet Stream meander south

During winter in the Northern Hemisphere, colder air over the Arctic shifts the polar jet south, bringing cold & wet weather to Northern Europe and the United States. During summer, the opposite occurs as warmer air from the Tropics moves into the region.

Jet streams do not follow a straight line but tend to follow wave-like and winding flows. These meandering flow are called Rossby waves, which are the result of variations in the Coriolis Effect, and the underlying topography on the planet's surface.

Rossby waves have a big effect on the weather of a region, as the dips and peaks in the waves bring entirely different weather to an area. Depending on its speed, Rossby waves can last for a short or very long period, enabling it to even affect climate patterns.

Jet streams also influence aviation. Due to its strong wind speed, airlines make use of it to reach their destinations faster with less energy. Flying against it must be avoided for obvious reasons, which is why airlines keep a close eye on the position of jet streams.   


The effect of jet streams is a lot more widespread than the few examples highlighted in this section, but these examples will help to explain how influential these powerful phenomena are in affecting weather globally, as well as the number of conditions it impacts.

Conclusion

As this article clearly illustrated, jet streams are one of the most crucial components in the forming of global weather patterns. They are formed in complex ways, and the explanations provided in this post were fundamental but enough to make it understandable.

In this article, we focused on explaining what a jet stream is and how it forms. The post also examined the different forms of jet streams and how each one is created.

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

Remember to join my Mailing List to be informed whenever a new article is released, and also receive helpful tips & information by simply  clicking on this link .

Until next time, keep your eye on the weather!

Wessel

1 2 3 9