A. Clouds and fogs differ only in one respect. Clouds are elevated above our heads: but fogs come in contact with the surface of the earth.
Q. If clouds are water, why do they float on the air?
A. 1st—The vapour of clouds is composed of very minute bubbles (called ves’cicles), which float like soap bubbles: and
2ndly—Warm air (between the bubbles) keeps them apart, and makes the mass lighter; and the currents of air (which constantly ascend from the warm earth) buoy them up.
Q. Why does vapour sometimes form into clouds, and sometimes rest upon the earth as mist or fog?
A. When the surface of the earth is warmer than the air, the vapour of the earth (being condensed by the chill air) becomes mist or fog. But when the air is warmer than the earth, the vapour rises through the air, and becomes cloud.
Q. Are all clouds alike?
A. No. They vary greatly in density, height, and colour.
Q. What is the chief cause of fog and clouds?