Eli5: why do wildfires get worse when temps are higher? Does a 10-20 degree difference (f) really matter? Does it just dry out the surrounding brush faster?
In: 2
basically yes.
drought is due to lack of rainfall and excessive heat. more heat = more evaporation = dryer plant life. more dry = better to burn. higher heat = more energy to start burning stuff with. take cooking an egg on the stove, setting 1 it might take 10 minutes, setting 10 it’ll take potentially seconds. same concepts with vegetation and plant life.
Pretty much. In an area that gets wildfires usually when it’s hot it is also dry, and combined with wind it dries the fuels out faster. It also makes the fuels warmer which makes a slight difference in how receptive it is to fire spread and ignition.
It’s essentially like heat setting fire to a sheet of paper. While it doesn’t need to be super dry, generally higher ambient heat reduces the amount of energy a wildfire would need to ignite more combustible (the brush, in this case). It is just that simple.
A great way to demonstrate a similar phenomenon: Fill two pots with a similar amount of water, but one must be as cold as your tap can make it, and the other as hot as your tap can make it. Put both of them on the stove, at a similar heat level. You’ll notice that the hot one boils first, because it takes less energy to boil what’s already warmer/hotter… Likewise, it takes less energy to set fire to what’s already hotter.
tl;dr: When the fuel is preheated by the weather it reaches ignition temperature more quickly. Yes, 10-20° differences can be significant in allowing wildfires to start.
“Fires spread in hot, dry, and windy conditions. Warmer temperatures and lower relative humidity make the fuels more receptive to ignition. Stronger winds supply oxygen to fire, preheating the fuels in the path of the fire, and transport embers ahead of the flaming front. When hot, dry, and windy conditions occur simultaneously, wildfires can spread quickly.”
Sources: https://www.noaa.gov/stories/ask-scientist-how-can-weather-spark-and-spread-wildfires
http://learnline.cdu.edu.au/units/env207/fundamentals/weather.html
It’s not only dryness, remember all you need to start a wildfire is energy, and heat is energy. When it gets hot, not only does it dry out, but it reduces the excess energy needed to create ignition.
Great responses below regarding how heat dries out plants and makes them easier to burn.
I’ll also add that heat is energy, and hot air has more energy than cold air. This energy can serve to create things like storms, lighting, tornadoes, etc. So not only does a heatwave lead to drying out the “Fuel” for the fire, it can also serve as the match to start fire by creating lighting storms.
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