Friday is here, and the 'Weekend Taste of Science' segment is back - number 107.
And this time, it's about the fascinating processes that occur at the heart of massive wildfires.
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The video is from the massive wildfires that recently raged in Spain, consuming over a quarter of a million dunams of forests. Such mega-fires have become almost a routine occurrence worldwide, and they pose a real threat to the Earth's ecological stability.
A forest fire is not fundamentally different from any other fire; it is based on a process called pyrolysis, in which, during the first stage, all the water in the combustible material evaporates. As the temperature continues to rise, the material breaks down into molecules and then into flammable gases like carbon monoxide, which burns easily upon contact with the hot air.
But massive wildfires have a power of their own, creating an independent and particularly interesting physical system around themselves.
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The fire spreads rapidly between the trees via electromagnetic radiation. The scorching heat of the burning plants radiates a great deal of energy in the form of light photons, which heat the surrounding trees and evaporate the water within them even before the fire itself arrives.
The currents of hot air within the fire push the flames forward and help the fire advance. The spread of the fire is also aided by burning embers flying through the air, creating new spot fires.
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The weather system around a massive wildfire is independent and disconnected from its surroundings.
The immense heat of the fire warms the air, which rises rapidly, and fierce winds of fresh air are sucked into the resulting vacuum. This air contains additional oxygen that continuously feeds the combustion process.
On its way up, the blazing hot air begins to cool, and the water vapor within it condenses into water droplets and clouds. The vapor turning into liquid releases a great deal of energy into the environment, which continues to rapidly push the cloud upward to an altitude where the water droplets freeze into ice.
When the ice crystals collide with one another, they discharge static electricity and create lightning, which can strike the ground around the fire and ignite new fires.
Sometimes these heavy clouds drift away from the center of the fire; the heavy, freezing air within them plummets rapidly to the ground, and upon impact, it creates sudden wind gusts of over 200 km/h. These wind gusts can alter the fire's direction in unpredictable ways.
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These processes are so powerful and colossal that they are still beyond our ability to control. The accepted approach today is to try to prevent the fire in advance through various means, and to contain the fire using fire retardants.
The effects of the fire on the local flora and fauna are no less fascinating, and we will learn about them in a separate segment.
Shabbat Shalom 😊
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👋 Hi, I'm Shlomo Strauss, and my posts are not written by artificial intelligence.
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