Science
posted by cathy .
The percent of atmosphere above and below 16.8 km is?

Do you want to calculate this?
Most of the atmosphere is below about 11 km. 100 km is deemed to be the point where the atmosphere stops.
16.8 km is usually taken as the top of the stratosphere. 
Here is the way to calculate that:
Pressure is the weight of the atmosphere above where you measure pressure.
Pressure at sea level is 760mm. Pressure at 16.8km is 75mm
So above 16km, the percent of the atmosphere is
percent=75/760 * 100
below that height, it is 100  that percent. 
I am working with a graph and if at every 5.6 km you cut in half the atmospheric mass. So at 16.8 km wouldn't you have 12.5% of the atmosphere above and 87.5% would be below?