IN­STANT EX­PERT: TOR­NA­DOES

Learn the facts, reap the whirl­wind.

Science Illustrated - - CONTENTS -

A full-fledged tor­nado is the most force­ful and scary phe­nom­e­non in our at­mos­phere. It is an in­ten­sive, ro­tat­ing air col­umn with the strongest wind on Earth, which stretches from a pow­er­ful thun­der­cloud to­wards Earth’s sur­face. Where the tor­nado reaches the ground, it leaves a path of con­cen­trated de­struc­tion.

Tor­na­does can oc­cur any­where on Earth ex­cept in the cold­est re­gions, but luck­ily, not many places in the world have the full set of in­gre­di­ents re­quired to pro­duce the most force­ful tor­na­does. Those you will find in ei­ther Mid­west­ern USA or Eastern In­dia and Bangladesh, where pe­ri­odic at­mo­spheric con­di­tions cause heavy show­ers. That could be the first step to­wards a tor­nado.

A tor­nado be­longs to the fam­ily of whirl­winds, and is sim­ply ro­tat­ing air. The term cov­ers any­thing from the rather in­no­cent dust devils with an ex­tent of a few me­tres, which are caused by lo­cal warm­ing of the ground, to ma­jor, ro­tat­ing low-pres­sure systems with an ex­tent of up to thou­sands of km. Water­spouts and willy-willies are es­sen­tially small tor­na­does. A tor­nado is the most pow­er­ful of all whirl­winds in the world.

The for­ma­tion prin­ci­ples of all of them are about the same. In­sta­bil­ity in the at­mos­phere causes in­tense thun­der­storms. Around and in­side the thun­der­storm, the whirls are pro­duced due to a se­ries of pro­cesses, of which the wind change with al­ti­tude and pow­er­ful lift are the cen­tral ones, which pro­vide the phe­nom­e­non with its vig­or­ous force.

In re­gions with in­tense tor­nado ac­tiv­ity such as the United States, a con­stant eye is kept on weather sit­u­a­tions which could pro­duce tor­na­does, and ex­perts try to pre­dict the sit­u­a­tion as well as pos­si­ble to al­low for prior warn­ing. How­ever, this is dif­fi­cult, even though the ex­perts are get­ting slightly bet­ter at it all the time due to more so­phis­ti­cated tools. It is dif­fi­cult to pre­dict the de­vel­op­ment of a thun­der­cloud and whether it is go­ing to de­velop into a tor­nado. So, in re­gions with risk of tor­na­does, it is nec­es­sary to con­sider safety, and many peo­ple have built spe­cial shel­ters for their fam­i­lies.

The ro­tat­ing wind of a tor­nado is the most force­ful on Earth. It can reach a speed of about 500 km/h, twice as much as the most force­ful trop­i­cal hur­ri­canes.

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