How to track a tornado - Karen Kosiba

View full lesson: http://ed.ted.com/lessons/how-to-track-a-tornado-karen-kosiba

Atmospheric scientist Karen Kosiba studies how tornadoes form and do damage. Getting measurements near the surface of these twisters is difficult, though, and driving into them is a practice mostly reserved for the big screen. In this TEDYouth Talk, Kosiba describes how she and her team use observations and modeling to track these super storms, while sharing some incredible footage from the field.

Talk by Karen Kosiba.

So, I think all good tornado talks

need to start with an awesome tornado shot.

And this is not that awesome tornado shot.

Alright, that was the first tornado I ever saw,

it was really cool,

it was really scary,

and the reason I'm showing it to you guys

was because that's why I got into the field

in the first place.

So, even though it's a bad photograph,

it was really cool to be out there the first time.

But now I'm taking real tornado footage.

Fast forward a few years here.

This is a few years ago

during a field project called VORTEX2,

where myself and a bunch of other scientists

were out there

surrounding tornadoes with different types of instrumentation

and trying to figure out how tornadoes form.

So, it's a big question

that we're trying to answer.

It sounds like a basic one,

but it's something that we're still trying to figure out.

We're also still trying to figure out

what the winds are like near the surface.

We know what the winds are like above building level,

but we really don't know what the winds are like

at the surface

and how that relates

to what we're seeing above building level.

So, most tornadoes form from what we call supercell thunderstorms,

and these supercell thunderstorms

are what you commonly think of as

tornado-raising storms.

They're big, rotating thunderstorms

that happen a lot of times in the midsection of the United States.

But the problem is that

even because they're rotating up above

doesn't mean they're rotating at the surface.

And when we look at these storms

and when we look at these pictures

and when we look at the data that we have

they all kind of look the same.

And it's really problematic

if we're trying to make tornado forecasts or tornado warnings

because we only want to warn on the storms

or forecast about the storms

that are going to actually make a tornado.

One of the big critical distinguishing features

that we think between these storms

is something about the rear flank downdraft.

So, these big rotating thunderstorms

have this downdraft that wraps around the rear edge of it,

hence the rear flanking downdraft.

But we think how warm that is,

how buoyant that air is,

and then also how strong the updraft

that's wrapping into

makes a big difference on whether or not

there's going to make a tornado or not.

And there's certainly a lot more that goes into it

and I'll tell you a little more about that in a second.

Once you actually get a tornado,

again, the problem that we have

is getting measurements near the surface.

It's really hard to get measurements near the surface

because most people don't want to drive into tornadoes.

There are a few exceptions,

and you might have seen them on TV shows.

But most people don't want to do that.

And even getting instrumentation in the path of the tornado

is pretty tricky, too

because, again, you don't want to be that close to a tornado

because sometimes the winds around the tornado are strong, as well.

So, getting information,

that critical location,

is key for us

because, again, we don't know

if the winds that we're seeing above ground level,

way above building level,

actually map to the surface.

if they're stronger, if they're weaker,

or if they're about the same as what we're saying above buildings.

The way that we get at answering a lot of these questions,

and I'm an observationalist, so I love to get out in the field,

I love to collect data on tornadoes,

we compile a lot of observations.

And I work with this group who operates these mobile radars,

and they're exactly what they say they are:

they're basically a radar on the back

of a big blue truck,

and we drive up really close to tornadoes

to map out the winds, we map out the precipitation,

we map out all these different things that are going on

in order to better understand the processes in these storms.

And that bottom there,

that's what a tornado looks like

when you're looking at it with a mobile radar

and when you're looking at it with a mobile radar real close.

Also, we do a lot of modelling,

so we do a lot of computer models and simulations

because the atmosphere is governed by the laws of physics,

so we can model the laws of physics

and see where the tornado might go,

where the storm might go,

how strong the winds are near the surface

and not actually have to go out in the field.

But, of course, we want to have both

observations and modelling

to move forward with the science.

So, this is,

I showed you that video earlier

that went real quick, too.

This is what it looks like when you're looking at it with a radar.

So you saw it visually,

but this is what I get really excited about

when I see now in the field

is stuff like this.

And the really exciting thing about

looking at stuff like this

is that this storm,

we caught it from when it didn't make a tornado

to when it made a tornado

and it intensified

and when it dissipated.

So, this is the one of the really rare data sets

that we have out there

that we're able to study the entire life cycle of a tornado.

I talked about that rear-flying down draft,

how we think that rear flanking downdraft is important

because it tilts, there's a lot of spin in the atmosphere,

but the problem with all this spin in the atmosphere

is it needs to be oriented vertically

because that's what tornadoes are doing,

and it needs to orientated vertically

near the ground.

So, we think this rear flanking downdraft,

we think that it just pulses,

and these pulses in this rear flanking downdraft,

we think are very important

for converging that rotation

but also getting that rotation into the right place.

Other things that we've learned

is that we have gotten a bunch of fortuitous measurements

in the path of the tornadoes

and very near the surface.

And we found out that the winds near the surface

are actually pretty comparable

to what we're seeing 30, 40 meters above ground level,

so there's not a big reduction in what we're seeing

above the surface to what we're seeing at house level.

And that was a pretty surprising finding for us

because we kind of assumed that

the winds decreased pretty substantially near the surface.

So I'm going to end it with this real quick.

And this is not my last tornado I ever saw,

but I really like this image

because this was taken with one of those mobile radars I was talking about.

And this is a tornado, not a hurricane,

and this is what it looks like

when you're really close to it.

And I find this amazing,

that we can actually take technology,

take technology this close to these types of storms,

and see these inner workings.

And for those of you who look at tornado images often,

you can see there's a lot going on there.

There's rain spiraling,

and you can actually see the debris cloud

associated with this tornado,

and I look forward to the future

and future technologies

and being able to learn a lot more about these storms

as the world advances,

as you guys contribute to the science,

and we're able to really learn more about how tornadoes form.

Thank you!