Tracie Howard, age 9, of Stillwater, Minn., for her question:

WHAT CAUSES HURRICANES TO TURN IN CERTAIN DIRECTIONS?

Hurricanes that hit the eastern seaboard of our country spiral around in a counterclockwise direction, as do all other hurricanes north of the equator. But those in the Southern Hemisphere spiral in a clockwise direction. In fact, all the winds and other objects moving above the earth are veered in opposite directions in the two hemispheres.

Spiraling winds and    clouds of a hurricane are controlled by a very complicated set of factors. They operate north and south of the equator as two opposite teams. Winds, planes and bullets moving toward the equator over the Northern Hemisphere are deflected to the right. Objects moving toward the equator above the Southern Hemisphere are deflected to the left. This is because of something known as the Coriolis effect.

If you tried to draw a straight line on a moving phonograph record, the line you would draw would be curved, since the outer part of the record is moving at a faster speed than the inner part. In somewhat the same way, the earth moves faster at the equator and its surface rotation speed decreases toward the poles.

The winds that blow above our earth are affected by the earth's rotation, but they lag somewhat behind. So, from our vantage point on earth, the winds appear to be deflected to the west, though actually the earth is moving around underneath. This deflection has    a lot to do with hurricanes. Most hurricanes form near the equator, where the winds are deflected most by the rotating earth. As the winds come toward the low pressure center of the hurricane, the Coriolis effect gives them a twist. And since the normal winds are twisting away to the west, they give the hurricane a counterclockwise push, which is helped by the turning of the earth underneath.  With the tremendous force of a hurricane, these initial twists are magnified many times to make storm winds up to 150 miles an hour.

The heart of a hurricane is a low pressure cell of warm, light, rising air. This calm eye of the storm may be 20 miles wide, but its column of light air draws in drafts of the denser air around it, maybe from as far away as 200 miles on all sides.

The storm begins to form as these faraway winds blow inward toward the central cell of low pressure. As a storm brews in the Northern Hemisphere, the winds move faster toward the eye and deflection bends them more sharply in a counterclockwise direction.