Teachers' Domain; Earth and Space Science; How Do Tornadoes Form?

Scientists are stumped about what causes any tornadoes large or small. How do you decipher the inner workings of a tornado. Meteorology in contrast to chemistry or biology is not a good laboratory science we can't produce an accurate representation a controlled representation of a thunderstorm and change the variables one by one to make tornadoes. No one can create a real tornado either on the plains of Moore in the lab. But there is one place where scientists can play puppets here with the weather. You know computer. The closest approximation we have are computer simulations and we try to build a digital computational model of the tornado and see if we can change variables and have storms that produce tornadoes and ones that don't. One of the leaders in tornado computer modeling is Lou Wicker. Thank you we're not going to.

Nine hundred twenty years ago I was and we are joined by eager storm chasers here tracking tornadoes the old fashioned way on the Open Planet Not really. A moving one. On the 70s in the early 80s we're just trying to understand what made storms work sort of visually. Now we're moving into an era we're trying to understand the dynamics of storms. Inside storm's dynamics means how the individual blobs of air are all interacting with each other to produce the flow that becomes either the strong winds or even a tornado or even most of the things that produce hail. Based on years of weather research. Lou produces an amazingly detailed computer simulation design with scientists at the University of Illinois. Into a supercomputer basic weather data wind speeds atmospheric pressure humidity. Then. The virtual storm grows on its own. And Lou sits back to see if a

tornado actually forms. A thunderstorm explodes into the atmosphere. The clouds begin to spin and roil. They descend closer to the ground. Still swirling rapidly. The dynamics of the digital storm are rendered in incredible detail. Warm air shown in orange rises into the storm until it slams into the jet stream above. The column of air begins to spin rapidly. Sure enough a tornado is born. And touches down to work. The question on everyone's mind is. What triggers that. Final step. What. Makes the tornado horror. Somehow supercell thunderstorms are able to bring. Intense rotation near the surface. And we don't understand the process very well. We know that

before 20 to forms there are areas of rotation in the thunderstorm. What we don't understand is how that rotation is brought down to the ground and intensifies in a very short period of time in order to make a tornado. In the search for a trigger. One of the primary suspects has been a burst of air descending from the storm. Called a downdraft. The idea. Is that the downdraft. Wraps around the storm. Tightening and intensifying the rotation. We think the downdraft is really important for producing the tornado because would help sort of squeeze the air from near the ground up into the updraft the air wraps around. And sort of the downdraft kind of comes around and squeezes the air in the front of the back together kind of squirt the air up off the ground. In the minutes before the twister forms. Storm chasers often see a downdraft blasting a hole in the clouds toward the rear of the storm.

Very impressive storm. The farthest along when I know. That. Truculent like good restaurants are coming down. Right. Pretty good. But just as often. The tornado fails to materialize. There must be more to the story. In addition to the downdraft who begins to discern the more subtle triggers for the tornado. To his surprise the model reveals that just as the storm intensifies a series of whirlwind forms at ground level. These tiny corkscrews of wind merge together into a much larger vortex of the tornado itself. The whirlwinds that show up in the computer are so subtle in real life they'd be invisible to the naked eye.

But is there any evidence they exist in nature. Blue Stein believes there is. We've been able to actually. Catch. 22 in the act of forming with a very very high resolution and what you see here you see a lot of small Voicebase you don't see one vortex becoming a tornado you see a number of small Voicebase. And the data proves it very chaotic and it's very complicated. It's not just a simple little downdraft here and just spins itself up there are lots of things going on at the same time and I think it captures a lot of the complexity that we see in the real world. All the evidence is pointing to an amazingly intricate dance of wind and moisture. Interacting with the environment. Including the terrain itself. The smallest changes can have a ripple effect. That. Can make the recipe just right for a tornado.