Patricia Keen, age 12, of Portland, Tenn., for her question:

 How are clouds formed?

This story begins with a ride up on an elevator. It continues with a flying carpet trip and ends with a dash on a down elevator. The water begins this merry jaunt on the face of the earth. The beaming sun powers the up elevator. It evaporates water from the surface of the sea, from lakes, rivers, puddles and damp soil.

When the water evaporates the liquid is turned into vapor. And vapor is a gas. It is so light that it soars aloft and blends with the other gases of the air. Above the earth, the air tends to be cooler. And cool air can hold less water than warm air. The vapor is squeezed into misty droplets. The water from the earth is now aloft in the form of a cloud. The cloud material is heavier than the vapor, but it is still light enough to float in the air. It becomes a flying carpet, blown hero and there by the Minds and the breezes.

Sooner or later, the misty droplets in the cloud grow still larger. They get together to form drops of rain, flakes of snow, or pellets of hail. These objects are heavier than the misty cloud material. Sooner or later they grow too heavy to stay aloft. Then they are at the mercy of the earth's gravity. And down, down they come. The water is returned to the earth and the c; 1a starts all over again.