Half of the mass of the atmosphere is found below an altitude of what because the air is compressed by the what of over laying atmosphere

The troposphere is denser than all its overlying atmospheric layers because a larger atmospheric weight sits on top of the troposphere and causes it to be most severely compressed. Fifty percent of the total mass of the atmosphere is located in the lower 5.6 km (3.5 mi; 18,000 ft) of the troposphere.

Explanation: hope this helps

1/0.14nm = 10^10/1.4 a lot