Vegetation and settlements in a desert are found near an_
Answers
Explanation:
Deserts are areas that receive very little precipitation. People often use the adjectives “hot,” “dry,” and “empty” to describe deserts, but these words do not tell the whole story. Although some deserts are very hot, with daytime temperatures as high as 54°C (130°F), other deserts have cold winters or are cold year-round. And most deserts, far from being empty and lifeless, are home to a variety of plants, animals, and other organisms. People have adapted to life in the desert for thousands of years.
One thing all deserts have in common is that they are arid, or dry. Most experts agree that a desert is an area of land that receives no more than 25 centimeters (10 inches) of precipitation a year. The amount of evaporation in a desert often greatly exceeds the annual rainfall. In all deserts, there is little water available for plants and other organisms.
Deserts are found on every continent and cover about one-fifth of Earth’s land area. They are home to around 1 billion people—one-sixth of the Earth’s population.
Although the word “desert” may bring to mind a sea of shifting sand, dunes cover only about 10 percent of the world’s deserts. Some deserts are mountainous. Others are dry expanses of rock, sand, or salt flats.
Kinds of Deserts
The world’s deserts can be divided into five types—subtropical, coastal, rain shadow, interior, and polar. Deserts are divided into these types according to the causes of their dryness.
Subtropical Deserts
Subtropical deserts are caused by the circulation patterns of air masses. They are found along the Tropic of Cancer, between 15 and 30 degrees north of the Equator, or along the Tropic of Capricorn, between 15 and 30 degrees south of the Equator.
Hot, moist air rises into the atmosphere near the Equator. As the air rises, it cools and drops its moisture as heavy tropical rains. The resulting cooler, drier air mass moves away from the Equator. As it approaches the tropics, the air descends and warms up again. The descending air hinders the formation of clouds, so very little rain falls on the land below.
The world’s largest hot desert, the Sahara, is a subtropical desert in northern Africa. The Sahara Desert is almost the size of the entire continental United States. Other subtropical deserts include the Kalahari Desert in southern Africa and the Tanami Desert in northern Australia.
Coastal Deserts
Cold ocean currents contribute to the formation of coastal deserts. Air blowing toward shore, chilled by contact with cold water, produces a layer of fog. This heavy fog drifts onto land. Although humidity is high, the atmospheric changes that normally cause rainfall are not present. A coastal desert may be almost totally rainless, yet damp with fog.
The Atacama Desert, on the Pacific shores of Chile, is a coastal desert. Some areas of the Atacama are often covered by fog. But the region can go decades without rainfall. In fact, the Atacama Desert is the driest place on Earth. Some weather stations in the Atacama have never recorded a drop of rain.
Rain Shadow Deserts
Rain shadow deserts exist near the leeward slopes of some mountain ranges. Leeward slopes face away from prevailing winds.
When moisture-laden air hits a mountain range, it is forced to rise. The air then cools and forms clouds that drop moisture on the windward (wind-facing) slopes. When the air moves over the mountaintop and begins to descend the leeward slopes, there is little moisture left. The descending air warms up, making it difficult for clouds to form.
Death Valley, in the U.S. states of California and Nevada, is a rain shadow desert. Death Valley, the lowest and driest place in North America, is in the rain shadow of the Sierra Nevada mountains.
Interior Deserts
Interior deserts, which are found in the heart of continents, exist because no moisture-laden winds reach them. By the time air masses from coastal areas reach the interior, they have lost all their moisture. Interior deserts are sometimes called inland deserts.
The Gobi Desert, in China and Mongolia, lies hundreds of kilometers from the ocean. Winds that reach the Gobi have long since lost their moisture. The Gobi is also in the rain shadow of the Himalaya mountains to the south.
Polar Deserts
Parts of the Arctic and the Antarctic are classified as deserts. These polar deserts contain great quantities of water, but most of it is locked in glaciers and ice sheets year-round. So, despite the presence of millions of liters of water, there is actually little available for plants and animals.
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