Meg Walsh, age 10, of Enid, Oklahoma, for her question:
What makes a tornado?
Tornadoes are born when gigantic storms clash high in the sky. Two great masses of air collide and start a weathery war. Lightning flashes and thunder roars like big guns. Wild winds lash through the dark grey clouds. The sky is full of trouble and we expect thunderstorms to deluge down on our heads. Sometimes this weathery warfare also hatches a batch of rampaging tornados.
Weather experts rate a tornado as the world's wildest storm. A hurricane is bigger, a blizzard is colder and a cloudburst is wetter. But a little tornado is the fiercest. The strongest wind is the fastest wind and a tornado's strength is a tunnel of wild whirling winds. Nobody is sure how fast the furious tornado winds can bloat. But experts think they reach speeds of 600 or even 700 miles per hour. This is much, much faster and stronger than the wildest hurricane.
The trouble builds up in the atmosphere on a very large scale. Imagine a gigantic mass of air, wide enough to spread across states and tall enough to reach six miles above your head. It is a mass of cool, dry air traveling along rather fast minding its own business. But it is not alone up there in the sky. Sprawled across its path there is a gigantic mass of warmish moist air.
The warm air is thin and light. It tends to float upward in bubbles and rising currents. The cool air is heavier and tends to stay closer to the ground. Around the world, masses of warm and cool air meet every day. As a rule, the heavier cool air wedges its way under the light warm air. There is a fairly gentle mixture of cool dry air and warm moist air and some fairly tame clouds form high in the sky.
But sometimes this does not happen. Instead, there is a head on collision and the cold air runs up and over the warm air. This upset creates a skyful of trouble, maybe over several states. The warm light air tries to rise through the cold heavy air above it. Then the spinning earth gets into the act. It twists the rising currents around and around like twirling ropes. As they spin faster and faster they form tornadoes.
Weather experts are not sure of everything that happens behind the scenes. But they assure us that tornados can be made when a mass of cold dry air climbs up and over a mass of mild moist air.
When tornados are hatching, the stormy sky is strewn with ragged grey clouds and patches of eerie yellow green light. Here and there the clouds dip down in twisting funnels that loots like elephant trunks. A tornado is born when one of those funnel tips touches the ground.