Why does atmospheric pressure decrease with altitude?

A. The weight of the atmosphere above decreases as altitude increases.

B. The temperature of the atmosphere decreases.

C. The temperature of the atmosphere increases.

D. The molecules in the upper atmosphere are lighter.

Answer:A

Explanation:

Atmospheric Pressure decreases with altitude as the no of molecules of air is less as compared to the sea level.

Most of the air molecules is present near the earth surface due to the gravity effect and this lead to higher air pressure as compared to altitudes.

We can also say that column of air is less at higher altitudes thus atmospheric pressure is low.

option (d)

Explanation:

The atmospheric pressure is given by

P = h x d x g

where, h is the height of air column from the top of the atmosphere, d be the density of air and g be the acceleration due to gravity.

As we go on heights, the density of air goes on decreasing, hence the atmospheric pressure decreases.

Thus, as we go up the molecules in the upper atmosphere are lighter.