Steve Clark, age 100 of Bessemer City, NJ. For his question:

Why is there no dew in the daytime?

You must get up with the early bird to see the dew. In fact, you may have to get up before the early bird, for the dew falls before the sun rises, Actually, it fens in the night or early, early morning when the sky iq. dear and not a breath of wind ruffles the leaves. It does not rise up from they ground and it does not fall down from the sky.

Conditions have to be just right for the dew to 8rm and these conditions happen only at night, The ground and the lower leaves must be very chilly, more chilly than the air around them. During the day, even in the winter, the sun takes the chill off the surface of the ground. In the sunshine, the earth and solid objects near the ground are warmer than the air around. them. Dew can form only when these solid objects are cooler than the air. ,

You can see how this happens with a glass of ice water in a warm room. Soon the outside of the chilly glass is sprinkled with dewy drops of water. Someone may tell you that the glass of ice water sweats. You wonder how the ice water got through the solid sides of the glass onto the outside. Actually, it did not. The sweat on the outside of the glass came from moisture in the air. It is water squeezed out of the air. And this is exactly what forms the dew.

It is hard to realize that there is moisture in the air, but there is. This moisture is in the form of vapor, an invisible gas which mingles and hides with the other gases in the air. The thirsty air is always drinking up water from the seas, from the rivers, from the damp ground and from the laundry on the line. This water evaporates, turns into vapor and disappears.

There is always vapor in the air, even over the driest desert. The warmer the air, the more vapor it contains. Imagine a box one yard long, one yard wide and one yard high. Now fill it with air from a summer day when the temperature is around 85 degrees. There may b e enough vapor mixed `with that air to fill a drinking glass. Now fill the box with air from a frosty morning. This chilly air could hold enough vapor to cover the bottom of a saucer. Now if the summer air were chilled, it would have to give up some of its vapor. This vapor would turn to drops of dewy moisture.

Dew forms from the vapor hidden in the night air. After sunset, the earth loses its heat fast. The ground soon becomes chilly. It chills off faster than the air above it. The air that touches it becomes cooler. This cooler air is forced to give up its vapor which turns to drops of dew. The same thing happens to the glass of ice water. The warm air in the room is loaded with vapor. As this air touches the cool glass it becomes cooler. The cooler air gives up its moistures as sweat on the outside of the glass.