Hot air always rises from the equator. As this air climbs higher in the sky, it cools. Cool air can hold less water than warm air. This means that as the air cools, clouds form that release most of the water they hold. Because the cooling air is above the equator, the moisture rains back down on the tropics.
The subtropical regions are the regions that lie between the tropical and the temperate regions in both the hemisphere. Here, the temperature remains high throughout the year, but slightly less than the temperate of the tropical and the equatorial areas.
Most of the deserts on earth lie in this zone. It favors maintaining a high temperature because of the absence or presence of very low humidity in this region. The air is very dry as a result of which it cannot form clouds, that are responsible for precipitation.
The desert areas are generally characterized by the high temperature, dry wind or low moisture content and lack of rainfall.
Absorption is a process that takes place in the small intestines or ileum of the GI tract, in which simple and soluble nutrients are absorbed into the blood stream.
Absorption is enhanced by several adaptations of the gut such as large surface area of the gut which directly facilitates absorption of nutrients.
Presence of villi and microvilli in the gut increases the surface area for absorption of nutrients in the ileum.
