Ronnie Melton, Age 12,, Of Gastonia, N.C.., for his question:

What is dew point?

Dew point is a term used by the meteorologist. It is the point at which the air is saturated with vapor, and we can expect some of this vapor to be changed into rain  Or fog or heavy dew. Water from the earth is constantly evaporating into vapor and joining the other invisible gases of the air. But the air can hold only so much of this vapor. Warm air can hold more vapor than cool air, however the meteorologist uses a chart to figure saturation or dew point. He takes the temperature and estimates the vapor content in a sample .cubic meter of air. If the temperature is 86 degrees and the sample contains 30:4 grams op vapor., the air is at dew point. Should the air become cooler., some of its vapor must be turned back into liquid water.