How do tornadoes form? - James Spann

10,065,353 views ใƒป 2014-08-19

TED-Ed


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

ืชืจื’ื•ื: Ido Dekkers ืขืจื™ื›ื”: Tal Dekkers
00:06
They call me the tornado chaser.
0
6969
2228
ื”ื ืงื•ืจืื™ื ืœื™ ืจื•ื“ืฃ ื”ื˜ื•ืจื ื“ื•.
00:09
When the wind is up and conditions are right,
1
9197
2519
ื›ืฉื”ืจื•ื— ืžืชื—ื–ืงืช ื•ื”ืชื ืื™ื ืžืชืื™ืžื™ื,
00:11
I get in my car and follow violent storms.
2
11716
3443
ืื ื™ ื ื›ื ืก ืœืžื›ื•ื ื™ืช ื•ืขื•ืงื‘ ืื—ืจื™ ืกื•ืคื•ืช ืืœื™ืžื•ืช.
00:15
"Crazy," you say? Perhaps, but really I chase these sky beasts to learn about them.
3
15159
5100
"ืžืฉื•ื’ืข," ืืชื ืื•ืžืจื™ื? ืื•ืœื™, ืื‘ืœ ืื ื™ ืจื•ื“ืฃ ืื—ืจื™ ืžืคืœืฆื•ืช ื”ืฉืžื™ื ื”ืืœื” ื›ื“ื™ ืœืœืžื•ื“ ืื•ืชืŸ.
00:20
I want to share with you what I know.
4
20259
2578
ืื ื™ ืจื•ืฆื” ืœื—ืœื•ืง ืื™ืชื›ื ืืช ืžื” ืฉืื ื™ ื™ื•ื“ืข.
00:22
Tornadoes are rapidly rotating columns of air that form inside storms
5
22837
4893
ื˜ื•ืจื ื“ื• ื”ื ืขืžื•ื“ื™ ืื•ื™ืจ ืฉืžืกืชื—ืจืจื™ื ืžื”ืจ ืฉื ื•ืฆืจื™ื ื‘ืชื•ืš ืกืขืจื•ืช
00:27
that connect with the ground via a funnel of cloud.
6
27730
3144
ืฉื ื•ื’ืขื•ืช ื‘ืื“ืžื” ื“ืจืš ืžืฉืคืš ืฉืœ ืขื ืŸ.
00:30
When that happens, they tear across the Earth,
7
30874
2508
ื›ืฉื–ื” ืžืชืจื—ืฉ, ื”ื ืงื•ืจืขื™ื ืืช ื”ืื“ืžื”,
00:33
posing a huge threat to life and property.
8
33382
3139
ื•ืžื”ื•ื•ื™ื ืื™ื•ื ืขืฆื•ื ืœื—ื™ื™ื ื•ืจื›ื•ืฉ.
00:36
Because of this, there's a great deal of research into these phenomena,
9
36521
3737
ื‘ื’ืœืœ ื–ื”, ื™ืฉ ื”ืจื‘ื” ืžื—ืงืจ ื‘ืชื•ืคืขื”,
00:40
but the truth is, there's still a lot we don't know about how tornadoes form.
10
40258
4728
ืื‘ืœ ื”ืืžืช ื”ื™ื, ื™ืฉ ืขื“ื™ืŸ ื”ืจื‘ื” ืฉืื ื—ื ื• ืœื ื™ื•ื“ืขื™ื ืขืœ ืื™ืš ื˜ื•ืจื ื“ื• ื ื•ืฆืจื™ื.
00:44
The conditions that may give rise to one tornado
11
44986
2385
ื”ืชื ืื™ื ืฉืื•ืœื™ ื™ื’ืจืžื• ืœื™ืฆื™ืจืช ื˜ื•ืจื ื“ื• ืื—ื“
00:47
won't necessarily cause another.
12
47371
2817
ืœื ื‘ื”ืจื›ื— ื™ืฆืจื• ืื—ื“ ืื—ืจ.
00:50
But we have learned a lot since people first started recording tornadoes,
13
50188
4278
ืื‘ืœ ืœืžื“ื ื• ื”ืจื‘ื” ืžืื– ืฉืื ืฉื™ื ื”ืชื—ื™ืœื• ืœืชืขื“ ื˜ื•ืจื ื“ื• ืœืจืืฉื•ื ื”,
00:54
like how to recognize the signs when one is brewing in the sky.
14
54466
4127
ื›ืžื• ืื™ืš ืœื–ื”ื•ืช ืืช ื”ืกื™ืžื ื™ื ื›ืฉืื—ื“ ืžืชื‘ืฉืœ ื‘ืฉืžื™ื™ื.
00:58
Are you coming along for the ride?
15
58593
1986
ื”ืื ืืชื ืžืฆื˜ืจืคื™ื ืœืžืกืข?
01:00
Tornadoes begin with a thunderstorm but not just any thunderstorm.
16
60579
4456
ื˜ื•ืจื ื“ื• ืžืชื—ื™ืœื™ื ืขื ืกื•ืคืช ืจืขืžื™ื ืื‘ืœ ืœื ื›ืœ ืกื•ืคืช ืจืขืžื™ื.
01:05
These are especially powerful, towering thunderstorms called supercells.
17
65035
4819
ืืœื• ืกื•ืคื•ืช ืจืขืžื™ื ื—ื–ืงื•ืช ื‘ืžื™ื•ื—ื“, ืžืชื ืฉืื•ืช ืฉื ืงืจืื•ืช ืชืื™ ืขืœ.
01:09
Reaching up to over 50,000 feet, they bring high force winds,
18
69854
3844
ืžื’ื™ืขื•ืช ืขื“ ืœื’ื•ื‘ื” 15,000 ืžื˜ืจ, ื•ื”ืŸ ืžื‘ื™ืื•ืช ืจื•ื—ื•ืช ื—ื–ืงื•ืช,
01:13
giant hailstones, sometimes flooding and great flashes of lightning, too.
19
73698
5746
ื‘ืจื“ ืขืฆื•ื, ืœืคืขืžื™ื ื”ืฆืคื•ืช ื•ื’ื ื”ื‘ื–ืงื™ื ืื“ื™ืจื™ื ืฉืœ ื‘ืจืงื™ื.
01:19
These are the kinds of storms that breed tornadoes,
20
79444
2885
ื–ื” ืกื•ื’ ื”ืกื•ืคื•ืช ืฉืžื™ื™ืฆืจื•ืช ื˜ื•ืจื ื“ื•,
01:22
but only if there are also very specific conditions in place,
21
82329
3999
ืื‘ืœ ืจืง ืื ื’ื ื™ืฉื ื ืชื ืื™ื ืžืื•ื“ ืžืกื•ื™ื™ืžื™ื ืฉืžืชืงื™ื™ืžื™ื,
01:26
clues that we can measure and look out for when we're trying to forecast a storm.
22
86328
4889
ืจืžื–ื™ื ืฉืื ื—ื ื• ื™ื›ื•ืœื™ื ืœืžื“ื•ื“ ื•ืœื—ืคืฉ ื›ืฉืื ื—ื ื• ืžื ืกื™ื ืœื—ื–ื•ืช ืกื•ืคื”.
01:31
Rising air is the first ingredient needed for a tornado to develop.
23
91217
4278
ืื•ื™ืจ ืขื•ืœื” ื”ื•ื ื”ืžืจื›ื™ื‘ ื”ืจืืฉื•ืŸ ืฉื ื“ืจืฉ ืœื”ืชืคืชื—ื•ืช ื˜ื•ืจื ื“ื•.
01:35
Any storm is formed when condensation occurs,
24
95495
2766
ื›ืœ ืกื•ืคื” ื ื•ืฆืจืช ื›ืฉืžืชืจื—ืฉืช ื”ืชืขื‘ื•ืช,
01:38
the byproducts of the clouds.
25
98261
2100
ืชื•ืฆืืช ื”ืœื•ื•ืื™ ืฉืœ ืขื ื ื™ื.
01:40
Condensation releases heat,
26
100361
2031
ื”ืชืขื‘ื•ืช ืžืฉื—ืจืจืช ื—ื•ื,
01:42
and heat becomes the energy that drives huge upward drafts of air.
27
102392
4284
ื•ื—ื•ื ื”ื•ืคืš ืœืื ืจื’ื™ื” ืฉืžื ื™ืขื” ืžืฉื‘ื™ื ื—ื–ืงื™ื ืขื•ืœื™ื ืฉืœ ืื•ื™ืจ.
01:46
The more condensation and the bigger the storm clouds grow,
28
106676
3345
ื›ื›ืœ ืฉื™ืฉ ื™ื•ืชืจ ื”ืชืขื‘ื•ืช ื•ื›ื›ืœ ืฉืขื ื ื™ ื”ืกื•ืคื” ื’ื“ืœื™ื,
01:50
the more powerful those updrafts become.
29
110021
2787
ื”ืžืฉื‘ื™ื ื”ืขื•ืœื™ื ื”ืืœื” ื ืขืฉื™ื ื—ื–ืงื™ื ื™ื•ืชืจ.
01:52
In supercells, this rising airmass is particularly strong.
30
112808
4561
ื‘ืชืื™ ืขืœ, ืžืืกืช ื”ืื•ื™ืจ ื”ืขื•ืœื” ื”ื–ื• ื—ื–ืงื” ื‘ืžื™ื•ื—ื“.
01:57
As the air climbs, it can change direction and start to move more quickly.
31
117369
4588
ื›ืฉื”ืื•ื™ืจ ืžื˜ืคืก, ื”ื•ื ื™ื›ื•ืœ ืœืฉื ื•ืช ื›ื™ื•ื•ืŸ ื•ืœื”ืชื—ื™ืœ ืœื ื•ืข ืžื”ืจ ื™ื•ืชืจ.
02:01
Finally, at the storm's base, if there is a lot of moisture,
32
121957
3080
ืœื‘ืกื•ืฃ, ื‘ื‘ืกื™ืก ื”ืกื•ืคื”, ืื ื™ืฉ ื”ืจื‘ื” ืœื—ื•ืช,
02:05
a huge cloud base develops, giving the tornado
33
125037
2744
ื‘ืกื™ืก ืขื ืŸ ืขื ืง ืžืชืคืชื—, ื•ื ื•ืชืŸ ืœื˜ื•ืจื ื“ื•
02:07
something to feed off later, if it gets that far.
34
127781
3670
ืžืฉื”ื• ืœื”ื™ื–ื•ืŸ ืžืžื ื• ืžืื•ื—ืจ ื™ื•ืชืจ, ืื ื”ื•ื ืžื’ื™ืข ื›ืœ ื›ืš ืจื—ื•ืง.
02:11
When all these things are in place, a vortex can develop enclosed by the storm,
35
131451
4123
ื›ืฉื›ืœ ื”ื“ื‘ืจื™ื ื”ืืœื” ื ืžืฆืื™ื, ืžืขืจื‘ื•ืœืช ื™ื›ื•ืœื” ืœื”ืชืคืชื— ืฉืชื—ื•ืžื” ืขืœ ื™ื“ื™ ื”ืกื•ืคื”,
02:15
and forming a wide, tall tube of spinning air that then gets pulled upwards.
36
135574
4946
ื•ื™ื•ืฆืจืช ืฆื™ื ื•ืจ ืจื—ื‘ ื•ื’ื‘ื•ื” ืฉืœ ืื•ื™ืจ ืžืกืชื•ื‘ื‘ ืฉืื– ื ืžืฉืš ืœืžืขืœื”.
02:20
We call this a mesocyclone.
37
140520
2324
ืื ื—ื ื• ืงืจื•ืื™ื ืœื–ื” ืžื–ื•ืฆื™ืงืœื•ืŸ.
02:22
Outside, cool, dry, sinking air
38
142844
2433
ืžื‘ื—ื•ืฅ, ืื•ื™ืจ ืงืจ, ื™ื‘ืฉ ื•ืฉื•ืงืข
02:25
starts to wrap around the back of this mesocyclone,
39
145277
2829
ืžืชื—ื™ืœ ืœื”ืชืœืคืฃ ืกื‘ื™ื‘ ืื—ื•ืจื™ ื”ืžื–ื•ืฆื™ืงืœื•ืŸ,
02:28
forming what's known as a rear flank downdraft.
40
148106
3123
ื•ื™ื•ืฆืจ ืžื” ืฉื™ื“ื•ืข ื›ืžืฉื‘ ืจื•ื— ื™ื•ืจื“ ืื—ื•ืจื™.
02:31
This unusual scenario creates a stark temperature difference
41
151229
3318
ื”ืžืฆื‘ ื”ืœื ืจื’ื™ืœ ื”ื–ื” ื™ื•ืฆืจ ื”ื‘ื“ืœ ื˜ืžืคืจื˜ื•ืจื” ื’ื“ื•ืœ
02:34
between the air inside the mesocyclone, and the air outside,
42
154547
3992
ื‘ื™ืŸ ื”ืื•ื™ืจ ื‘ืชื•ืš ื”ืžื–ื•ืฆื™ืงืœื•ืŸ ื•ื”ืื•ื™ืจ ื‘ื—ื•ืฅ,
02:38
building up a level of instability that allows a tornado to thrive.
43
158539
4141
ื•ื‘ื•ื ื” ืจืžื” ืฉืœ ื—ื•ืกืจ ื™ืฆื™ื‘ื•ืช ืฉืžืืคืฉืจืช ืœื˜ื•ืจื ื“ื• ืœืฉื’ืฉื’.
02:42
Then, the mesocyclone's lower part becomes tighter,
44
162680
2878
ืื–, ื”ื—ืœืง ื”ืชื—ืชื•ืŸ ืฉืœ ื”ืžื–ื•ืฆื™ืงืœื•ืŸ ื ืขืฉื” ืฆืจ ื™ื•ืชืจ,
02:45
increasing the speed of the wind.
45
165558
2682
ืžื” ืฉืžื’ื‘ื™ืจ ืืช ืžื”ื™ืจื•ืช ื”ืจื•ื—.
02:48
If, and that's a big if, this funnel of air moves down
46
168240
3299
ืื, ื•ื–ื” ืื ื’ื“ื•ืœ, ืžืฉืคืš ื”ืื•ื™ืจ ื”ื–ื” ื ืข ืœืžื˜ื”
02:51
into that large, moist cloud base at the bottom of the parent storm,
47
171539
3873
ืœืชื•ืš ื‘ืกื™ืก ืขื ืŸ ื’ื“ื•ืœ ื•ืœื— ื‘ืชื—ืชื™ืช ืกื•ืคืช ื”ืื,
02:55
it sucks it in and turns it into a rotating wall of cloud,
48
175412
3578
ื”ื•ื ืฉื•ืื‘ ืื•ืชื• ืคื ื™ืžื” ื•ื”ื•ืคืš ืื•ืชื• ืœืงื™ืจ ืžืกืชื•ื‘ื‘ ืฉืœ ืขื ืŸ,
02:58
forming a link between the storm that created it and the Earth.
49
178990
3836
ื•ื™ื•ืฆืจ ืงืฉืจ ื‘ื™ืŸ ื”ืกื•ืคื” ืฉื™ืฆืจื” ืื•ืชื• ื•ื”ืื“ืžื”.
03:02
The second that tube of spinning cloud touches the ground,
50
182826
2580
ื‘ืฉื ื™ื” ืฉืฆื™ื ื•ืจ ื”ืขื ืŸ ื”ืžืกืชื•ื‘ื‘ ื ื•ื’ืข ื‘ืงืจืงืข,
03:05
it becomes a tornado.
51
185406
2222
ื”ื•ื ื”ื•ืคืš ืœื˜ื•ืจื ื“ื•.
03:07
Most are small and short-lived, producing winds of 65-110 miles per hour,
52
187628
5731
ืจื•ื‘ื ืงื˜ื ื™ื ื•ืงืฆืจื™ ื—ื™ื™ื, ืžื™ื™ืฆืจื™ื ืจื•ื—ื•ืช ืฉืœ 100-180 ืงื™ืœื•ืžื˜ืจ ืœืฉืขื”,
03:13
but others can last for over an hour, producing 200 mile per hour winds.
53
193359
5250
ืื‘ืœ ืื—ืจื™ื ื™ื›ื•ืœื™ื ืœื”ืฉืืจ ื™ื•ืชืจ ืžืฉืขื” ื•ืœื”ื’ื™ืข ืœืจื•ื—ื•ืช ืฉืœ 320 ืงืž"ืฉ.
03:18
They are beautiful but terrifying,
54
198609
2421
ื”ื ื™ืคื™ืคื™ื™ื ืื‘ืœ ืžืฆืžืจืจื™ื,
03:21
especially if you or your town is in its path.
55
201030
3305
ื‘ืขื™ืงืจ ืื ืืชื ืื• ื”ืขื™ืจ ืฉืœื›ื ื‘ื ืชื™ื‘ ืฉืœื•.
03:24
In that case, no one, not even tornado chasers like me,
56
204335
3365
ื‘ืžืงืจื” ื”ื–ื”, ืืฃ ืื—ื“, ืืคื™ืœื• ืœื ืจื•ื“ืคื™ ื˜ื•ืจื ื“ื• ื›ืžื•ื ื™,
03:27
enjoy watching thing unfold.
57
207700
3065
ื ื”ื ื™ื ืœืจืื•ืช ืืช ื”ื“ื‘ืจื™ื ืžืชืงื“ืžื™ื.
03:30
Just like everything, however, tornadoes do come to an end.
58
210765
3813
ื›ืžื• ื”ื›ืœ, ืขื ื–ืืช, ื˜ื•ืจื ื“ื• ื‘ืกื•ืคื• ืฉืœ ื“ื‘ืจ ื ื’ืžืจื™ื.
03:34
When the temperature difference disappears and conditions grow more stable,
59
214578
3688
ื›ืฉื”ืคืจืฉ ื”ื˜ืžืคืจื˜ื•ืจื” ื ืขืœื ื•ื”ืชื ืื™ื ื ืขืฉื™ื ื™ื•ืชืจ ื™ืฆื™ื‘ื™ื,
03:38
or the moisture in the air dries up,
60
218266
1948
ืื• ืฉื”ืœื—ื•ืช ื‘ืื•ื™ืจ ืžืชื™ื™ื‘ืฉืช,
03:40
the once fierce parent storm loses momentum and draws its tornado back inside.
61
220214
5427
ื”ืกื•ืคื” ืฉืคืขื ื”ื™ืชื” ืื“ื™ืจื” ืžืื‘ื“ืช ืžื•ืžื ื˜ื•ื ื•ืžื•ืฉื›ืช ืืช ื”ื˜ื•ืจื ื“ื• ื—ื–ืจื” ืคื ื™ืžื”.
03:45
Even so, meteorologists and storm chasers like me will remain on the lookout,
62
225641
4844
ืขื ื–ืืช, ืžื˜ืื•ืจื•ืœื•ื’ื™ื ื•ืจื•ื“ืคื™ ืกื•ืคื•ืช ื›ืžื•ื ื™ ื ืฉืืจื™ื ื‘ื›ื•ื ื ื•ืช,
03:50
watching, always watching to see if the storm releases its long rope again.
63
230485
5315
ืฆื•ืคื™ื, ืชืžื™ื“ ืžื—ืคืฉื™ื ืœืจืื•ืช ืื ื”ืกื•ืคื” ืชืฉื—ืจืจ ืืช ื”ื—ื‘ืœ ื”ืืจื•ืš ืฉืœื” ืฉื•ื‘.
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

https://forms.gle/WvT1wiN1qDtmnspy7