Keith Wiley., age 12, of Phoenix, AZ.

What is the jet stream?

The bet streams were discovered over the Pacific by pilots of World Tar II. Each one is a tunnel of high speed winds blowing like a long, thin ribbon for thousands of miles around the globe. The ribbon is a flat tube, about 300 miles wide and four miles deep, The wind is fastest in the center of the snaky tunnel, where it blows anywhere from 50 to 250 miles per hour.

Over North America, there are usually three bet streams snaking their windy way from west to east. They blow between four and eight miles above the ground and their wavy paths vary from day to day.