Desert

* Desert is a region that receives little rain (of zero to the 500 milliliters per year) and that it has a high index of atmosphericevaporation, that is, is a place that loses more water of what it earns.

* Some polar regions are considered desert-like by receiving little rain (about 250 milliliters per year), however, in these regions, the evaporation of the water of the ground is almost null, had the white color of the snow that reflects the heat, and the humidity of air is high.

* In a conventional desert the time is almost always dry, the hot days and the cold nights.

* Although the image that if has of the desert, with sand mounts without end, the sand alone occupies 20% of the total area of the deserts of the world.

* It is resulted of the accumulation of loaded sediments for the wind. Most of the sand is in the deserts that are in the region of the trade winds, that are two current forts of wind that if they form for the heating of air next to the equatorial region. In this region it is the desert greater of the world, the Saara.

* The region of the trade winds also is very hot, therefore the strong winds push clouds, aumentanto the amount of solar rays that happen on the land.

* The majority of the deserts is full untied gravel plains and rocks. Some, that in the past had been stream beds of lakes and rivers, present accumulations of salt, plaster and precious rocks. The desert of the Atacama, in Chile, for example, is a great sodium nitrate reservoir, known as salitre.

* The animals and plants that inhabit the deserts have capacities special to keep the internal humidity. Scorpions and other insects have exoesqueleto (carapaça) harder than the normal one. It functions as a tank, keeping the heat is. Mammals and small reptiles are entocados the day all, only leave to feed themselves during the night, when he is more cold. Beyond if not burning in the sun, the breath inside of the sultry burrow leaves the environment most humid.

* The plants that survive in the desert are tolerant dry and to the salt. They store water as she will be possible, in caule, the root or even in leves. Some possess well long roots to reach freáticos sheets.