need to start with an awesome tornado shot.

竜巻の凄い写真をお見せするのが一番

And this is not that awesome tornado shot.

これは そんなに凄くありませんが

Alright, that was the first tornado I ever saw,

私が初めて見た竜巻です

it was really cool, it was really scary,

見事でしたが 恐ろしくもありました

and the reason I'm showing it to you guys

この写真をお見せする理由は

was because that's why I got into the field in the first place.

これがきっかけで 竜巻を追い始めたからです

So, even though it's a bad photograph,

大したことのない写真ですが

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

実際に初めて見た竜巻には感動しました

But now I'm taking real tornado footage.

今は もっとすごい 竜巻の映像を撮影しています

Fast forward a few years here.

数年先に進めます

This is a few years ago

これは数年前のこと

during a field project called VORTEX2,

VORTEX2というプロジェクトで

where myself and a bunch of other scientists were out there

多数の科学者とフィールドで観測を行いました

surrounding tornadoes with different types of instrumentation

様々な装置を竜巻周辺に設置し

and trying to figure out how tornadoes form.

竜巻発生の仕組みを 突き止めようとしました

So, it's a big question that we're trying to answer.

これは 難しい問題です

It sounds like a very basic one,

簡単そうですが

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

まだ分かっていないのです

We're also still trying to figure out

いまだもって地表付近の風の様子を

what the winds are like near the surface.

調べている段階です

We know what the winds are like above building level,

建物より上の風の様子は分っていますが

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

地表付近の風については さっぱりですし

and how that relates to what we're seeing above building level.

建物より上の風との関係も不明です

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

多くの竜巻はスーパーセルと呼ばれる 雷雲から生じます

and these supercell thunderstorms

このスーパーセルこそが

are what you commonly think of as tornado-raising storms.

おなじみの竜巻の原因となる積乱雲です

They're big, rotating thunderstorms

この巨大な回転する雷雲は

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

アメリカの中央部で頻繁に発生しています

But the problem is that

問題なのは

even because they're rotating up above

上の方では渦を巻いていても

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

地表付近で回転しているとは限らず

And when we look at these storms

これらの積乱雲を観察し

and when we look at these pictures

写真やデータを見てみると

and when we look at the data that we have

写真やデータを見てみると

they all kind of look the same.

どれも同じように見えることです

And it's really problematic

これでは 竜巻予報や

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

竜巻警報を出すのが難しくなります

because we only want to warn on the storms

竜巻を実際に引き起こす

or forecast about the storms

積乱雲に対してだけ

that are going to actually make a tornado.

警報や予報を出せないからです

One of the big critical distinguishing features

竜巻に成り得る積乱雲を見分ける

that we think between these storms

重要な特徴は

is something about the rear flank downdraft.

「後方下降流」であると 考えています

So, these big rotating thunderstorms

この巨大な回転する雷雲の

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

後方の縁を包み込むように吹く下降流なので

hence the rear flanking downdraft.

そう呼ばれています

But we think how warm that is,

これがどの程度暖かく

how buoyant that air is,

浮力が働いているか

and then also how strong the updraft

また一方で上昇流が いかに強く

that's wrapping into

巻き込んで流入しているかが

makes a big difference on whether or not

竜巻を発生させるかどうかの

there's going to make a tornado or not.

決め手になると考えています

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

勿論もっと多くの要因があるので

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

後でもう少し詳しく話します

Once you actually get a tornado,

実際に竜巻に遭遇できたとしても

again, the problem that we have

問題は先ほどお話ししたように

is getting measurements near the surface.

地表付近での測定を行うことです

It's really hard to get measurements near the surface

これは実に難しいのです

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

大抵の人は竜巻に 車で突入したくないですからね

There are a few exceptions,

でも これをやる人もいます

and you might have seen them on TV shows.

テレビで見たことがあるかもしれませんね

But most people don't want to do that.

しかし普通やりたくありません

And even getting instrumentation in the path of the tornado is pretty tricky, too.

竜巻の進路に測定装置を 設置するのでさえやっかいです

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

やっぱり竜巻に近づきたくないですからね

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

竜巻周辺の風が強くなることも ありますから

So, getting information, that critical location, is key for us.

でも このような要所で データを得ることが大事なのです

Because, again, we don't know

というのも

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

地表より上の 建物よりずっと高い場所での

way above building level,

風の様子が

actually map to the surface.

地表におけるものと比べて

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

強いのか 弱いのか

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

それとも同じ程度なのか 分かっていないからです

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

このような疑問に答えるために

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

観測を行う科学者として 竜巻の起こる場所で

I love to collect data on tornadoes,

データ収集に打ち込んでいます

we compile a lot of observations.

沢山のデータの集積が必要なんです

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

このような移動式レーダーも 使っています

and they're exactly what they say they are:

その名の通り 青い大型トラックに

they're basically a radar on the back of a big blue truck,

レーダーを積んだだけのものですが

and we drive up really close to tornadoes

これを竜巻の直ぐ近くまで走らせ

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

風と雨量をマップ化します

we map out all these different things that are going on

様々なデータを進行形で観測し

in order to better understand the processes in these storms.

積乱雲の中で起きていることを 把握しようとします

And that bottom there,

下の図が

that's what a tornado looks like

移動式レーダーで観測した

when you're looking at it with a mobile radar

竜巻の様子を示しています

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

とても近づいて測定したものです

Also, what we do is we do a lot of modeling,

さらに コンピュータ・モデルを作成したり

so we do a lot of computer models and simulations

シミュレーションもたくさん行っています

because the atmosphere is governed by the laws of physics,

大気は物理の法則に従いますから

so we can model the laws of physics

物理法則でモデル化し

and see where the tornado might go,

竜巻の動きや

where the storm might go,

積乱雲の動き さらに

how strong the winds are near the surface

地上付近の風の強さを

and not actually have to go out in the field.

実際に現場に行かずに予測できます

But, of course, we want to have both observations and modelling

もちろん 観測とモデルの両方が

to move forward with the science.

科学の進歩のためには必要です

So, this is, I showed you that video earlier that went real quick, too.

これは先ほど ちょっとお見せした ビデオです

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

レーダーで見るとこんな感じになります

So you saw it visually,

視覚的に見ることができます

but this is what I get really excited about

現場に出て

when I see now in the field

この様な画像を見ると

is stuff that looks like this.

とても興奮します

And the really exciting thing about looking at stuff like this

このような画像が

is that this storm,

特に素晴らしいのは

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

まだ竜巻が発生する前の積乱雲の状態から

to when it made a tornado

竜巻が発生し

and it intensified

成長し そして

and when it dissipated.

衰えるまでを捉えたからです

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

これは 我々が取得した

that we have out there

特に貴重なデータで

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

竜巻の一生を研究することができます

I talked about that rear-flying down draft,

先ほど 「後方下降流」 が

how we think that rear flanking downdraft is important

重要だと考えていると お話ししましたね

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

スーパーセルの中では 空気がグルグル回っていますが

but the problem with all this spin in the atmosphere

いくら 回転力があっても

is it needs to be oriented vertically

回転の軸が縦にならなくては

because that's what tornadoes are doing,

竜巻にはなりません

and it needs to orientated vertically near the ground.

しかも 地表付近で縦でなければなりません

So, we think this rear flanking downdraft, we think that it just pulses.

この「後方下降流」は パルス状だと考えていますが

And these pulses in this rear flanking downdraft,

このパルスが

we think are very important

空気の回転を揃えて

for converging that rotation

その回転を傾け

but also getting that rotation into the right place.

竜巻発生に必要な向きにする 重要な鍵だと考えています

Other things that we've learned

さらに学んだのは

is that we have gotten a bunch of fortuitous measurements

竜巻の進路上や地表すれすれで

in the path of the tornadoes

うまく 得られた

and very near the surface.

たくさんのデータから

And we found out that the winds near the surface

地表付近の風は

are actually pretty comparable

地上30－40mにおける

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

風の様子とあまり変わらないことも 分かりました

So there's not a big reduction in what we're seeing above the surface

つまり屋根より上で吹く風の勢いは

to what we're seeing at house level.

地表近くでほとんど衰えていないわけです

And that was a pretty surprising finding for us

これは驚きの事実です

because we kind of assumed that

地表付近では大幅に

the winds decreased pretty substantially near the surface.

風の勢いが弱まると考えていたからです

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

最後に この画像をお見せします

And this is not my last tornado I ever saw,

これは 一番最近見た 竜巻ではありませんが

but I really like this image

例の移動式レーダーで取ったもので

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

とても気に入っています

And this is a tornado, not a hurricane,

竜巻です ハリケーンではありませんよ

and this is what it looks like

とても近くでは

when you're really close to it.

こんなふうに見えるんです

And I find this amazing,

すごいですよね

that we can actually take technology,

竜巻にいろいろな装置を

take technology this close to these types of storms,

こんな近くまで持って行って

and see these inner workings.

内部の仕組みも知れるなんて

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

竜巻の映像に見慣れてくると

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

色々なことが起きているのが分かります

There's rain spiraling, and you can actually see the debris cloud

渦状の降雨地域や デブリ（木々や建物の破片）の雲まで

associated with this tornado,

見ることができます

and I look forward to the future and future technologies

将来もっと技術が進化し

and being able to learn a lot more about these storms

竜巻についてもっと理解が 進んで欲しいと願っています

as the world advances,

科学が進化し―

as you guys contribute to the science,

そう 皆さんが科学に貢献し

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

竜巻の形成について もっと分かるようになるでしょう

Thank you!

どうも有難う！