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When wildfires happen, we use models  to predict how they’ll spread, but those models are missing  some critical information.

Like how wildfires can make themselves  stronger by changing the weather. Without understanding how wildfires  literally make themselves worse, we could be putting people and property in danger, especially as the climate crisis intensifies.

As our climate changes, many  parts of the world are expected to undergo warmer springs, and  longer summer dry seasons. That means forested areas  are more likely to dry out, which means fire danger increases. That will make it easier for fires to start.

What’s more, with more people  moving into wildland areas, those fires are more likely  to put human life at risk. And fighting wildfires can be way more  difficult than fighting house fires. Wildfires often start in remote areas,  and can become massive very quickly.

That means that in order to fight fires  safely, firefighters need to know how, when, and where any individual  fire is likely to spread. To figure that out, they use complex  computer models which take into account the type of terrain the fire is burning in  and how much fuel the fire has access to. In our current wildfire landscape,  though, that just isn’t good enough.

That means we’re going to have to  figure out what else affects wildfires, so that we can update our models. And one of the most important factors  we need to consider is the weather. The big issue is wind.

While strong winds can snuff out small fires, they only enhance larger fires  by literally fanning the flames. And fires are likely to travel in  the same direction as the wind. Prevailing wind patterns can  push fires in one direction, keep them in place for longer, or even  split them into two separate fires.

But while we do incorporate  wind forecasts into our models, those forecasts look at how  wind blows on a large scale; think atmospheric fronts  or enormous storm systems. They don’t look at wind patterns on small scales, like how wind can curve around a mountain, or how a narrow path between two  peaks can become a wind tunnel. That happened in the Redwood Valley fire in 2017.

Weather models didn’t take into account a tiny, 11-kilometer gap in the mountains of  Northern California, but the wind did. Winds rushed through the gap,  creating a small wind tunnel that carried the fire along with it. Again in 2018, winds coming  downslope from the nearby mountains pushed a fire into the town  of Paradise, California, killing 85 people and  virtually destroying the town.

Wind can also pick up embers and carry  them far away from the main fire. If those embers find the right conditions,  they can flare up into new wildfires. That means an updated fire model will  have to pay attention not only to which way the wind is blowing,  but where embers could land and whether those embers are  likely to form new fires.

And those are just existing weather conditions. Strong enough fires can also  change the weather in their favor. Fires cause plumes of hot air and smoke to  rise, and when the fire is large enough, those plumes can get pretty  far into the atmosphere.

When the plumes hit cooler air in  the high levels of the atmosphere, they cool down. Water vapor condenses  out of them, forming storm clouds. These clouds are common enough features of large fires that they have their own name.

Usually, they’re referred to  as pyrocumulonimbus clouds. Unfortunately, unlike most storm clouds, these clouds don’t tend to release a lot of rain. And when they do, it can  sometimes make fires worse.

When rain falls into dry air, it evaporates,  creating a sudden burst of cooler air. This change can affect the wind patterns,  creating a downburst around the flames. These downbursts can spread embers, causing new ignitions farther away from the fire.

And remember that plume that formed  the cloud in the first place? As it rose, it would have  also altered wind patterns, creating a massive updraft of warm air. That updraft can create unpredictable  winds too, including deadly fire tornadoes.

Yes, you heard that right. Fire tornadoes. Fire can cause masses of air  to rotate, forming a tornado.

We’ve only observed this twice,  once in Australia in 2003, and once in the Carr Fire in California, in 2018. In the Carr Fire, that firenado had  winds clocking in at 140 miles per hour. And not only did the tornado kill four  people, it also spread the fire further.

If that isn’t enough, remember that thunderstorms also come with lightning, and  lightning can start new fires. Altogether, that makes for a lot of complex  factors that contribute to fire spread. That means predicting which way any  fire is going to move is not easy.

Thankfully, there’s a whole field of science trying to tackle these issues  from different perspectives. Researchers are figuring  more things out every day, tracking fires from spark to  finish, and working directly with emergency teams to make sure  they’re using the most updated data. And they are making progress.

Updated models which take  wind patterns into account have been able to map past fires accurately. That means that when we take  the models and feed them the same conditions as historical fires, the simulations they produce line up with  how the fires actually spread in reality. It’s not that far of a stretch to go from that  to predicting how future fires will develop.

As these models grow to take into  account more and more parameters, it won’t be long until they  can be used in real time. In a wildfire situation, this could be lifesaving. And we’re going to need these  updated models now more than ever.

Even if we act aggressively  to cut carbon emissions, we have to accept that even if we  stopped burning fossil fuels today, climate change is already here. Which means learning how to  survive in a changed world with more frequent, more intense wildfires. And hopefully keep more people safe.

If you wanna help us keep  making videos about how science can save lives and also fire tornadoes,  consider supporting us on Patreon. We have some neat perks available to Patrons, plus you’re directly involved  in making educational stuff that anyone can watch for free. So if you’re already a patron, thank you.

And if you’re not, you can get  started at patreon.com/scishow. [♪ OUTRO]