Name: How Do Tornadoes Form? - Instant Egghead #37
Uploaded: 2017-05-11T00:34:50.000Z
Duration: 1 min 51 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Tornadoes occur in every continent, except Antarctica

but more form over the central United States than anywhere else

That's because conditions  in the Alley are ideal

Warm humid air low  to the ground moves north

and collides with cool dry air  high above the ground

The collision of air masses  creates a supercell,

a massive thunderstorm  that has a strong rotating updraft of air.

Scientists aren't exactly sure  what happens next

The difference in speed between the faster high winds

causes the air in between to rotate around the horizontal axis.

If one end of the rolling air  gets caught on the updraft

can then push down  on the tail of the funnel cloud

until it reaches the ground,  forming a tornado.

and most touch the ground for less than ten minutes.

However, extreme tornadoes  are truly extreme.

The longest tornado path was cut  by the Tri-State tornado on March 18, 1925.

It was on the ground  for well over three hours

Which is why I'll be hanging out in here,

For Scientific American,  Instant Egghead. I'm Mark Fischetti.

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How Do Tornadoes Form? - Instant Egghead #37

massive

extreme

instant

continent