At the end of 2019, Australia suffered a natural disaster - severe forest fires broke out in different parts of the country. They reached the limits of the city of Barnesdale on December 30. People and animals left dangerous areas. But soon the situation became even worse.
Firestorms
After forest fires spread throughout Australia, a new problem arose. It is about the formation of firestorms that carry hot coals for many kilometers.
When a forest fire begins, a lot of smoke enters the atmosphere. Its concentration in the upper layers increases, which leads to the formation of small white clouds.
Such clouds can turn into a full-fledged thunderstorm in just 30 minutes. Large-scale thunderstorms resulting from fires generate not only lightning, but also strong winds, which are a big problem.
Hot streams of air pick up pieces of a burning tree and carry them to remote areas. As a result, fires also begin to occur there.
According to Nicholas McCratney, an Australian scientist studying forest fires at the University of Queensland, the dangers of such firestorms are hard to overestimate.
Pyrocumulative clouds can produce a short destructive effect or take the form of real fire storms. Such a natural phenomenon can significantly increase the scale of fires, transferring fire to those areas where it was not.
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Some statistics
In 2018, a massive fire was recorded in California, called the Carr. Then the diameter of the pyrocumulative cloud in 15 minutes increased from 5 to 11 km.
As a result, a large fire tornado was formed, which caused numerous destruction. We are talking about 71.6 hectares of scorched earth, the death of 8 people and more than 1000 destroyed houses.
Similar firestorms formed in other places. Fire tornadoes have been spotted in Texas, Arizona, and Portugal.
Many scientists are convinced that frequent natural disasters of this type are the result of heating the Earth. Global warming has resulted in the driest spring and hottest year.
According to experts, storm fires can occur more often and become stronger. This means that forest fires will also increase.
Storm formation
Michael Flannigan, a professor of wildland fires at the University of Alberta, is convinced that predicting the occurrence of firestorms will be extremely difficult.
They are formed under the influence of the same factors that lead to forest fires. It is a strong wind and dry hot air.
When the trees begin to burn, the air masses over them heat up and ascending gusts of wind appear. As a result, the smoke leaves sharply vertically in the form of a column and enters the atmosphere.
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The rising hot air cools after a while, condensation forms and clouds appear. According to Michael, the farther hot air goes up, the more likely it is that a thunderstorm will happen.
The scientist claims that due to the rapid rise of air inside the storm, its own wind field appears, forming a very stormy air environment.
Fire Storm Features
Thunderstorms form on the basis of pyrocumulative clouds, but only lightnings that strike trees and the earth have a positive rather than negative charge. The main difference between such "positive" lightning is the increased duration of the impact of the spark charge on the environment. That is, lightning strikes longer.
For this reason, the risk of fire after such thunderstorms is significantly higher than with standard options.
The situation is further complicated by the fact that thunderstorms resulting from fires produce virtually no rain. And in case of fire, rain that can extinguish the fire will not.
The lack of precipitation is due to the fact that thunderstorms form on the basis of smoke.
Another feature of firestorms that you should be aware of is the low level of their mobility. They hardly move, remaining above the source of ignition that formed them.
