Answer:
Hot, humid air rises over the equator. As it rises to high altitude it expands because the air pressure decreases (there is less mass of air above it). As air expands due to this decreasing pressure, it also cools. Since cool air is able to hold less water vapor than warm air, condensation occurs.
Yes the do increase heart rates.
The exosphere is the furthest out layer.
Hope this helps!
Add all of those up and you have your answer.
