The word tornado is derived from the Spanish word tronada, meaning 'thunderstorm', which itself is derived from the Latin word tornare which means 'to make round by turning'.

The tornado, also known as a 'twister', is by far the most violent of Earth's atmospheric disturbances. This destructive weather phenomenon has been responsible for widespread destruction and countless deaths around the world, but America's mid-west Kansas area is the hardest hit.

Tornadoes are extremely powerful vortexes, emanating downwards from highly charged cumulonimbus clouds. Their rotational velocities have been shown to average around 500 kilometres per hour, but on some occasions they've been observed to exceed speeds of 800 kilometres per hour.

Recognising Tornadoes for the Layman

Right, let's set the scene.

You're stuck in the middle of Tornado Alley¹. The bright sunlight you've been used to seeing over the last few days is beginning to fade, overshadowed by the growing numbers of dark and forbidding clouds overhead. Are you gonna get hit by the most devastating force on Earth?

Don't know? Then read on...

Stages

• The first thing you need to do is watch those big black cumulonimbus clouds. If you see what is known as a funnel-cloud² sticking out the bottom of one of those black storm-clouds then this could be the beginnings of a Tornado.

• As the funnel-cloud develops, growing bigger and blacker, it will start to dip earthwards as more and more debris is forced into the intensifying vortex.

• Now it's time to make a hasty retreat. All the signs are pointing to the manifestation of a full-blown tornado, and it's only a matter of time before the finger of God strikes earthwards.

• As you make your retreat to safety, keep an eye on the mother-cloud that spawned the tornado. Make sure you move away from the direction of travel of the mother-cloud as it will drag the tornado along with it.

  The forward motion of a tornado is usually around 50 kilometres per hour, but it could be a lot more (up to 100 kilometres per hour in exceptional circumstances), so you really need to keep your wits about you, and drive as fast as you can.

  Usually the motion is from the southwest to the northeast and they don't tend to be more than a few hundred metres across and their actual ground travel is not often more than 30 kilometres.

So, to sum up, keep a good road-map handy, watch the base of the cumulonimbus clouds, especially keeping an eye out for the funnel-cloud, and if you can stay near a good highway, you should be able to outrun most tornadoes, if you're lucky.

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¹ Tornado Alley is the corridor of maximum occurrence of tornadoes in the US, and has an average of 27 tornadoes annually.
² A funnel-cloud is a small cloud-shaped protuberance that sticks out from the bottom of a cumulonimbus cloud, seemingly just hanging there, yet still attached to the main cloud base.