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.
X would equal 5. (need more characters)
E0 ellipticals are nearly circular, while E7s are very stretched out. Elliptical galaxies are made up of mostly old stars, and do not have much gas and dust. There is very little new star formation in these galaxies.
Mostly made of old stars
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