Dan Ray Clagett, age 10,

How much does the air weigh?

We live at the bottom of a great ocean of air, which stretches up hundreds of miles above our heads. We are so used to it that we do not notice it. Yet this vast atmosphere presses down upon the whole earth with terrific weight. The air in an empty coffee cup weighs about as much as a grain of wheat. The air in a fair sized room weighs several pounds, The great blanket of air around the globe weighs about five quadrillion tons. That figure is five followed by 1 5 zeros.

The air pressure over each square inch of the earths surface varies with height and temperature. At sea level it is about 14 and a half pounds. On top of a mountain three and a half miles high the air pressure is about seven and a quarter pounds. Half the weight of the entire atmosphere is crowded in the lower layer, from the earth to some seven miles above its surface.