Gary Owens, age 13, of Aurora, Ohio, for his question:

What exactly are the jet streams?

The Gulf Stream is a swift current of water flowing through the ocean. A jet stream is a swift current of air blowing through the upper atmosphere. It may be a help or a hazard to high flying aircraft. The experts cannot predict exactly when or where it will blow, and a pilot is never surf when his plane may run into one of these gale winds of the stratosphere.

Many thoughtful people feel that the 20th century has neglected the science of meteorology.    Compared with space experts and other scientists, our trained weathermen are overworked and short of funds to probe the secrets of the turbulent atmosphere. We must know, for example, far more about the jet streams. These tricky gales blow 20,000 to 40,000 feet above the Earth in the upstairs region of modern aviation. Jet streams were discovered in World War II by high flying pilots crossing the Pacific. Since then, we have gathered enough data to chart three typical jet stream paths in the northern hemisphere. But we cannot predict the wild meandering course of a jet stream or when it will blow. Three jet stream paths rip across the upper air lanes of North America.

A jet stream is a flat, waving ribbon of winds about 300 miles wide and four miles thick. It is a wild wind tunnel with the strongest breezes in the center. At ground level winds reach hurricane speed at 75 miles an hour. In winter, the average wind speed down the core of a jet stream is 100 miles an hour and extremes may reach 250 miles an hour. The tunneling winds are somewhat slacker in summer. The lofty gales blow from the west and meander from side to side without warning. The atmosphere at these lofty levels is usually clear, and wild regions of turbulent air tend to occur at the invisible edges of the high speed jet streams.

So far we have only theories to explain the cause of the tricky jet streams. They seem to hatch in the tropopause, a thin layer of the atmosphere above the weathery troposphere. Here the contrast in air temperature is strong, and most meteorologists suspect that this factor may create or help to create the streaming wind tunnels. The propopause is a thin shell of calm air broken into a series of globe circling bands. The wild jet streams hatch where these flat bands of the tropopause overlap, and when we know more about the tricky antics of the upper atmosphere we may be able to explain why this is so.

The troposphere is the weathery layer of the lower atmosphere. It reaches 11 miles above the equator and dips to five miles above the poles. Its temperature decreases steadily on the way up and begins to rise again in the stratosphere layer above it. The tropopause is the thin boundary between the calmer stratosphere and the turbulent troposphere. The gusty jet streams born in the tropopause rip through the upper troposphere and far into the lofty stratosphere above it.