Diane Hughes, age 11, of Lethbridge, Alta., Canada, for her question:

WHY DOESN'T IT HAIL IN WINTER?

No one is surprised when hailstones come pelting down from a stormy summer cloud. But none of us expects hail in the winter. However, this is possible. As a matter of fact, hail often falls far out on a sea during winter nights. It happens only when conditions are just right in the atmosphere. Hail, like rain and snow, is formed from gaseous water vapor in the air. Temperature and other factors determine whether this moisture will fall in liquid drops, in icy pellets or fluffy flakes.

Weathermen tell us that hail forms when there is a steep temperature gradient. This means that warm air near the surface chills fast at higher levels. Under these conditions, misty moisture aloft is likely to form hail as it drops down through the air. Over most land areas, this temperature pattern aloft occurs most often in summer   which is why hail formation is rare in winter.