Vicki Roane, age 8, of Mooresville, Ind., for her question:
Why is a tornado cloud black?
if Mother Nature had a vacuum cleaner, it would be a whopper. It would pull up the dirt and dust and big chunks of debris. It would even lift up big solid objects such as cars and trees. Such a monster vacuum cleaner could easily knock over a house or a whole town. This, of course, is just what a tornado does. And, if we wish, we may think of it as Mother Nature t s vacuum cleaner.
A vacuum is an empty space. You might think that you know where there are lots of empty spaces around, but this is not quite true. The empty spaces between the furniture, for instance, are filled with air: So is the empty space in your pocket or in a cave. In our world, the empty spaces are almost all filled with air. And a vacuum is a space in which there is no air, or only a trace of air.
A hole in the air acts very much like a hole in the water. It does not stay there. Try to scoop a hole in a pailful of water. You can take out a scoop of water easily enough. But the water around it flows in at once to fill up the hole. Air behaves in just the same way. When a patch of air is drawn away, the air around it blows in to fill up the almost empty space.
The vacuum cleaner is a machine which makes a hole in the air on purpose. It does this with a motor and a fan. When you turn on the switch, a patch of air is sucked away at the end of the vacuum cleaners hose. The air around this little vacuum rushes in to fill up the hole. It rushes in with enough force to pull along the dust and dirt. A. good vacuum cleaner is strong enough to pick up bits of paper and matchsticks.
The funnel at the heart of a tornado is a much bigger, much stronger vacuum cleaner. Actually it is a tunnel of warm, light air rising up so fast that there is almost no air at all. The surrounding air blows in to fill up this hole in a great hurry. This rushing air is the wind that blows with a tornado. It blows so fast that it knocks over anything in its path. The spinning earth gives a twist to these winds and they spiral inwards to the funnel of the tornado. It also carries along a great quantity of dust, dirt and debris.
At the funnel of the cloud, the winds are swept upward at a great speed. They take with them all the dusty debris. This is what makes the funnel of the tornado dark. There may also be raindrops in the funnel, for the tornado is really a fierce little storm. All of this dark, dusty material rises up in the center of the tornado. As the wild little storm wears itself out, this material will be dropped on the ground. It may be dropped far, far from where it was picked up by the rushing winds.