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What Is A Microburst? — Definition, Types, And More

Have you ever heard of microbursts? These not-so-small phenomena can engineer wind speeds, packing a punch more powerful than some tornadoes. A microburst is essentially a smaller-scale downdraft with significant destructive potential.

These microbursts involve a burst of sinking air that drops from the heart of a thunderstorm toward the ground. This sudden descent sets off a surge of high-speed winds.

The National Weather Service reports that microbursts are compact. They typically measure no more than 2.5 miles in diameter. Despite their petite size, these natural phenomena can produce wind speeds up to 100 miles per hour that can hold for about five minutes. 

Although it's a brief period, a microburst can wreak massive havoc on life, property, and the aviation industry. Read on to learn more about this atmospheric phenomenon.

Related Read: Environmental Impact of Wind Energy

Types of Microbursts 

wet microburst
Wet Microburst, Photo by NOAA Legacy Photo ERL/WPL on Flickr licensed under CC BY 2.0

There are two types of microbursts: wet microbursts and dry microbursts

A wet microburst is a downward air thrust resulting from heavy rainfall, hail, or a storm. This phenomenon is primarily influenced by a mid-level dry air mass and precipitation, creating a potent mixture of powerful winds and heavy rainfall. 

Alternatively, a microburst can occur without precipitation reaching the ground, termed a dry microburst. These are characterized by minimal or no precipitation and winds dispersing unpredictably, often leading to dust or sand being swept into the air. 

Some microbursts exhibit both wet and dry attributes – we categorize these as hybrid microbursts. 

As previously stated, a microburst can inflict severe wind damage, impacting populations, infrastructure, and natural environments, with airlines often experiencing the most substantial harm. 

Given this, it's crucial to consider a severe thunderstorm warning as seriously as a tornado warning. You must seek shelter immediately.

What causes microbursts? 

So, what causes a microburst? Well, it all starts with the formation of a thunderstorm and the suspension of hail and water droplets within an updraft. 

If an updraft gets so strong, it holds massive rain and hail in the top parts of the thunderstorm. 

Many factors could lead to the evaporation of cooling air, which weakens the updraft. Cool air is denser and sinks downward, creating a downdraft. As the updraft weakens, it becomes more challenging to hold larger amounts of rain and hail. 

As a result, the rain and hail charge toward the ground, dragging a lot of downdraft air. When the downdraft lands on the ground, it turns into a downburst that spreads outward in all directions.

However, the first location where the microburst hits the ground experiences the highest winds, causing damaging straight-line winds. 

Microbursts and aviation 

storm and strong winds
Photo by NOAA National Severe Storms Laboratory on Flickr (Public domain)

It will interest you to know that the study of microbursts is relatively new. 

Before the introduction of Doppler radars and other new technology at major airports, microbursts were responsible for many airline accidents. Before then, investigators blamed the airline accidents on pilot error and other factors. 

One particularly gruesome airline accident was the crash of Delta Airlines Flight 191.  

Pilots prepared to land the aircraft as a severe thunderstorm hovered. However, as pilots lowered the plane toward the runway, a downburst of winds knocked the airplane full of passengers to the ground, where it moved and hit an automobile driver, shoving right into two large water tanks and bursting into flames. Sadly, only 27 people survived this accident. 

The Delta Airlines Flight 191 crash became a central point for microburst research, leading to the introduction of the Doppler radar in 1988 and better aviation safety measures1.  

Some airports have wind sensors that help detect a microburst. With this wind sensor, pilots and air controllers can work to keep the aircraft away from storms. 

Can you predict a microburst? 

A microburst happens in small areas so fast and is short-lived. This makes it a bit tricky to predict them in advance. 

However, meteorologists can predict conditions that aid the formation of this straight-line wind. They do this by monitoring several factors, including high precipitable water, strong winds aloft in a dry layer, dry air in mid-levels, and other conditions that can cause the development of a microburst. 

Typically, forecasters can only predict microbursts a few hours before their formation.  Forecasters can also detect a microburst on a weather radar. They look out for converging air streams in the middle section of the thunderstorm. 

When forecasters detect the formation of a microburst early, they send out severe thunderstorm warnings. However, because a microburst is short-lived, lead times for severe thunderstorm warnings may be very short. In some cases, there may be no thunderstorm warning at all. 

The best way to protect yourself from a microburst is to pay attention to warnings of severe thunderstorms just as you pay attention to tornado warnings. If you’re living in an RV or manufactured home, you will need to seek shelter in a sturdy building until the storm passes.

Where does a microburst occur? 

Microbursts occur throughout the U.S., but they differ by region. Tropical climates, mainly in the Southeastern area, often experience wet microbursts. In contrast, dry climates in the Western states typically deal with dry microbursts. 

Even though a microburst can happen anytime, they are most common in the spring and summer months.

Other types of damaging winds

downburst
Photo by Péter Kövesi on Unsplash

Microbursts are one of the most severe types of damaging wind that destroy human lives, properties, and dozens of trees. However, they are not the only type of violent wind. 

In this section, we will look at some types of damaging wind2

Straight-line wind 

A straight-line wind is a wind from thunderstorms not associated with rotation. Unlike tornadoes, straight lines push debris in the same direction as the wind, hence the term “straight line.” 

If straight-line wind damage occurs, downed trees and power lines appear knocked down in the same direction. Tornadoes, on the other hand, will scatter debris in different directions. 

However, a straight-line wind can be so strong that people think a tornado appeared. Microbursts can produce straight-line damage, leading to the destruction of trees, buildings, and properties. 

Macroburst 

A macroburst occurs when a strong downdraft reaches the surface. So, peak winds arise near the surface at a dimension much larger than 2.5 miles. 

This wind may start in a small area and spread out to a broader area, producing a catastrophe similar to tornado damage. 

Downburst

We refer to a downburst when severe thunderstorms generate an intense downdraft. These powerful winds dive quickly from within a thunderstorm, strike the ground, and disperse in all directions.

Downbursts can be categorized as either macrobursts or microbursts, depending on the size of the area they impact. Macrobursts cover larger areas, while the typically seen downbursts are microbursts that affect a more localized region.

The downburst process has phases: the Contact stage, the Outburst stage, and the Cushion stage. The Contact stage marks the point when the roaring winds from the thunderstorm touch down, wreaking significant damage with its force.

Following this, during the Outburst stage, the air from the downburst fans out from its initial point of contact, generating a curving movement along its leading edge.

The final stage is the Cushion stage, where the initially ferocious winds and storms at the contact start to diminish as the winds spreading outward travel gradually.

Ultimately, the winds decelerate, and the microburst fades out. However, their effects can devastate an average home, with the potential to rip off roof sections and shatter windows, doors, and other structural elements.

Gust front 

A gust front or outflow boundary is the foremost edge of a rain-cooled air that collides with a warmer storm inflow. In other words, a gust front is a line wind that separates a cold downburst from a storm from warm surface air.  

So, during a gusty front, you will see temperature drops, wind shifts, and gusty winds ahead of a storm. You may see the wind push up some air above them, forming a shelf cloud. 

Derecho

Derechos are long-lived storms that involve bands of storms and showers. So, a derecho can consist of groups of microburst, downburst, and downburst clusters in a straight line. They are fast-moving and can cause destruction similar to that of a tornado. 

Haboob

A haboob is an intense dust storm propelled along the ground from a storm downburst with high acceleration. So, when a downburst reaches a surface, it begins to blow up loose silt and clay from the surface, creating a wall of dust. 

This type of wind is common in Middle Eastern countries like Sudan and continents like North America and Australia. 

Microburst vs Tornado 

effect of strong wind to trees
Trees felled by microburst winds in Utah, Photo by Brian Wangrud on Wikimedia Commons licensed under CC BY-SA 3.0 (Cropped from original)

While both can destroy lives, properties, trees, and other structures, a microburst and a tornado are very different weather phenomena. 

While a microburst is a downburst of powerful winds hitting the earth and causing straight-line damages, a tornado appears in a violent spinning of winds, causing damages to appear in a twisted and circular pattern.

Both microbursts and tornadoes can produce increased wind speeds and cause significant damage. 

Tornadoes tend to have longer paths of destruction, and you can sometimes see them on the ground. 

Conclusion 

Microbursts are a relatively new discovery in the world of meteorology. Many years ago, it was challenging to predict a microburst, which led to several airline accidents. Thanks to advancements in technology, several tools can help identify the formation of a microburst, reducing casualties. 

1

Roberts, R. D. (1989). A proposed microburst nowcasting procedure using Single-Doppler radar. AMETSOC.

2

Damaging Winds Types. (n.d.). NOAA National Severe Storms Laboratory.

By Jennifer Okafor, BSc.

Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.

Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.

Photo by NOAA on Unsplash
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