Final answer:
Air pressure decreases exponentially with altitude above the tropopause, following the formula p(y) = poexp(-ay).
Step-by-step explanation:
The student asks about how air pressure changes above the tropopause. The answer is that air pressure decreases exponentially with altitude. Atmospheric pressure is described by the formula p(y) = poexp(-ay), where p(y) represents the pressure at height y, po is the pressure at the surface, and the constant a is the pressure scale height. Air pressure does not decrease at a constant rate (option A) nor increases exponentially (option C). As one ascends through the atmosphere, the density of air decreases due to the gravitational pull becoming weaker, which, in turn, causes the pressure to drop. This decrease is exponential in nature because the higher you go, the thinner the air becomes, leading to a rapidly declining pressure.