Explain why , atmospheric pressure decreases as we go higher up above the earth's surface.

Explanation

Air in the atmosphere is not the same at all levels. It is more dense near the earth. It goes on thinning out as we go up. So, there being more density of air near the earth, there is more air pressure. As the density of air goes on decreasing, its weight and consequently the air pressure goes on decreasing with increase of height.