Welcome to You Ask Andy

Timothy Cooper age 10, of Evarly, Iowa,

A whirlwind seams to appear from nowhere,, usually in the middle of a calm, hot summer day  It may arrive at a scorching street corner and trip from side to aids across the hot pavement, lifting stray scraps of paper and fallen leaves high over the roof tope  It may arrive in a dry field with a soft whisper and a swirl of grasses  But the whirlwind is most at home on the prairies and the hot deserts  Here it is a column of whirling duet and sandy debris waltzing this way and that, often in a company of five or six of its relatives 

The desert whirlwind is often called a dust devil, which is hardly fair  True, you may sat a face full of gritty dirt if you walk through the little dancer  But it does not move fast and you can usually dodge it, Only very rarely is s whirlwind big and strong enough to do any serious damage  And actually, it does more good than harm, The desert whirlwind whisks soma of the scorching hot air near the surface and lifts it aloft  Cooler air then flows down to take its place  The dainty little dent®r helps to cool off the desert heat and is really a friend,

The twirling column of air inside a whirlwind may remind you somewhat of the dusty tunnel of a dipping tornado  But the two are caused by entirely different weather conditions and era not at all related  The furious tornado dips its column of whirling air down to the ground, The twirling air of the whirlwind rises up from the ground,

A whirlwind occurs when the air near the surface of the ground is much hotter than the layer of air above it  The air gets its heat from the grounds which is warmed by the rays of the sun  On a scorching summer day, the thin layer of air next to the ground may become very hot indeed, especially when there are no breezes to pool it, This is when a whirlwind is likely to be on 

A patch of the warm air near the surface begins to expand arms vise  This creates a column of air which is thinner, leas denser than the air surrounding it  When this happens, the surrounding air rushes in to the thin area to even things up, for in many ways air behaves very much like water  If you take a dipper full of water from a bucket, the surrounding water flows in to fill up the hole, In the atmosphere, denser air tends to flow and blow in to fill up a pocket of thinner air 

In the whirlwind, the surrounding air flows into the canter from all sides  As it moves in, it starts to spin around and around in a spiral  Along the way it grabs bite of paper, loose leaves or a few handfuls of dusty sand, At the center, the column of warm air is rising  The dusty debris is whisked aloft with it and often left to fall far from where it was picked up,

As the air expands, it cools itself  The warm, rising air at the center of the whirlwind may reach a few hundred or even 1,000 feet above the ground  Up there, 3t has become cool* A patch of the hottest air near the surface has been removed and the ground or the desert is a little cooler than it would have been without the dancing whirlwind 
Category: Article series 1960

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