How much does a column of air weigh?

Answer 1

Water's mass depends on its purity. The old definition of a gram was the mass of one ml of pure water at 0 degrees C.

The mass of a column of water is therefore approximately one gram per ml, where the number of ml is the column's length in cm, times 2pi times its radius in cm squared.

Now, weight is proportional to mass and the inverse square of the distance between two bodies. One body is the column of water and we'll assume the other to be the earth. Assume this column of water is "close" to the earth and a good estimate for the weight is 9.81 times the water's mass.

On the earth's surface, at 0 deg C, a column of pure water's mass, in grams, is approximately 9.81*L*2pi*r2 with L and r in cm.

Answer 2

At sea level, a column of air has a mass of about 10 tonnes per square meter; that is equivalent to 100,000 newton per square meter = 100,000 pascal.