Linda Lee Bullock, age 12, of Fort Deposit, Alabama, for her question:

Why does the dew fall at night?

Dew does not fall like rain, nor does it ooze up from the ground, as some people think. It forms when gaseous water vapor in the air condenses into drops of water. This happens because the amount of vapor in the air depends on temperature. Warm air can hold more vapor than cool air. When the temper ature drops, some of the vapor in the air may be changed into liquid drops of dew.

The earth's daily quota of solar warmth ends when the sun sets. Through the night, no more is added and some of the day's quota gradually escapes. The earth becomes coolest in the early pre dawn hours    and the cool air chills the air above it. If this air was loaded with vapor, the lowered temperature makes it necessary to change some of its vapor into liquid water. This is when the world becomes drenched with pearly dew drops