The Effects of Desert WeatherA desert is a type of landscape that receives littleprecipitation. Deserts are normally defined as areas that receive annual precipitation of less than 250mm. But some places such as Tucson, Arizona receive more but are still called deserts. That is because they have a much higher rate of evaporation.Many environmentalists argue that desert regions are increasing. This process is called desertification. It happens when useful soil is blown away by wind. Then the temperature rises, and an area that was once fertile becomes desert. They say that this is due to global warming. It is also due to overdevelopment. Both of these problems are major threats to humanity.True deserts have very sparse vegetation. These deserts exist in the most arid regions of Earth. In these places, rainfall is rare and infrequent.Deserts have a reputation for supporting little life. But this is not true. Deserts have many animals that hide during daylight. About one fifth of the Earth is covered in desert.Desert landscapes are often composed of sand and rocky surfaces. Sand dunes and stony surfaces called regs are often found in deserts. Cold deserts have similar features but receive snow instead of rain. Antarctica is the largest cold desert. The largest hot desert is the Sahara.Most deserts have an extreme temperature range. The temperature is very low at night. This is because the air is so dry thatitholds little heat. The desert cools as soon as the sun sets. Cloudless skies also increase the release of heat at night.Sand covers only about 20% of Earth's deserts. There are six forms of deserts. One of the forms is a mountain or a basin desert. Hamada deserts are comprised of plateau landforms. Regs consist of rock pavements. Ergs are formed by sand seas. Intermontane basins occur at high elevations. Finally, Badlands are arid regions comprised of clay-rich soil.What is the main idea of the passage...