Well, I don't know this off the top of my head, but we can figure
it out... According to my science book, the air pressure at sea level
is 14.7 psi. This means that if you took a column of air one square
inch wide that went all the way up through the atmosphere, it would
weigh 14.7 pounds. So in order to figure out how much the whole
atmosphere weighs, all we need to do is figure out how many square
inches make up the surface of the earth.
We can do this using the earth's radius, 3965 miles. This is the
same as roughly 2.512*10^8 inches (or 251,200,000 inches). Since the
earth is a sphere, we can use the equation for the surface area of a
sphere, 4*pi*radius^2 (or 4*3.14*radius*radius). This gives us
7.93*10^17 square inches on the earth. Multiplying this by 14.7 pounds
per square inch says that the atmosphere weighs about 1.17*10^19 pounds
(or about 11,700,000,000,000,000,000 pounds)! That's a lot of air!
(republished on 08/01/06)