The number of wildfires across the world has been increasing at a record speed in the last few years. Not only that, the carbon dioxide emission has been at a record high. With August 2021 releasing the highest amount of CO2 due to wildfire i.e. 1.3 Gigatonnes, as measured by Copernicus Atmosphere Monitoring Service.
Carbon Dioxide emissions are not the only impact that wildfires have on us and our planet. There are a lot of other things like reduction in vegetation, forested area, loss of flora and fauna and a lot more. As our understanding of Climate Change is increasing, so are its impacts. Today, we would take a look at the science behind these Wildfires. What causes them? How do they expand to such a massive area within a few hours? And, how do they cause so much damage in such a small time?
Wildfires: Causes
Wildfires can start on their own accord due to some natural phenomena like lightning or reaching an ignition point from Sun's heat. But most of them are started by humans, either unknowingly or deliberately. Some causes include campfires in forests, arson, throwing still lit matches, cigarettes, etc.
The Fire Triangle is the three components that are needed to start a fire. It includes fuel (wood and other forest products in this case), oxygen supply and heat source to reach the ignition point. As a fire starts when it gets the three components of the fire triangle, several other factors determine its life and intensity.
If the fuel supply is low, the fire would burn with low intensity and its spread would be slow as well. But, it the fuel supply is a lot, both the intensity and spread would be high. Another property of fuel that determines the intensity is the moisture content, shape and size. The drier the fuel, the faster it burns and spreads. Higher the surface area to volume ratio, quickly it will burn and vice versa. Temperature affects wildfires in the same way, they dry out the load and make them more flammable.
How does fire spread?
Fire dries out the materials in its vicinity making them more flammable by evaporating the moisture. Wind also plays an important role in the spreading of fire. As it provides oxygen as well as push the burning material in a particular direction at a much faster rate.
If you have ever been to a hilly area, you know that it's easier to go downhill than uphill. But, fire follows the opposite rule. Fire can spread faster uphill than downhill. The reason behind this is that the direction of the ambient wind is uphill which aids the fire to travel faster. Apart from that, the heat from the fire below preheats the load above and it becomes easier to burn. But, the same doesn't happen downhill. So, a wildfire struggles to spread at the same rate downhill.
This was the science behind wildfires. So, next time you go on a camping trip with friends and family keep in mind to avoid anything that may cause a wildfire because it burns our most important assets.
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