What are the climatic characteristics of the desert?

Desert climate is also called desert or dry climate. Due to different latitudes, it can be divided into three types: tropical desert, subtropical desert and temperate desert. Desert climate is one of the most important factors to form desert environment. The present desert climate has evolved through geological and historical periods. The unique climate of desert is a rich resource for human activities, but it also brings disasters, such as sandstorms, heat waves and floods. Desert climate-Introduction Desert climate is the extreme situation of continental climate. It is the most widely distributed in the subtropical desert. The basic reason is that there is little rain, plants are difficult to survive, and the species and quantity of plants are extremely rare. The ground is bare, the air is very dry and there is little moisture. During the day, the solar radiation is strong, and the ground temperature rises rapidly, and the temperature can reach 60 ~ 70℃. The updraft is strong, but because the air is dry, there are few clouds and little rain, only strong winds and dust. At night, the ground temperature drops extremely, even below 0℃. Therefore, the temperature varies greatly every day. Can be as high as above 50 DEG C.. Although Taklimakan Desert in Xinjiang belongs to temperate desert, "wearing cotton yarn in the morning and eating watermelon in the stove" is not a sensational legend, but a realistic life picture. Rainfall in desert climate is scarce, generally less than 50 mm. Although Ruoqiang is on the edge of the desert, the annual rainfall is only 17.4 mm, and the minimum rainfall is only13.9 mm in 957. The annual rainfall in Turpan is only 16.3mm, and 1968 is only 2.9mm. With so little rain, agriculture can be developed on the edge of Taklimakan desert. Planting rice, wheat, corn, cotton, grapes, watermelons, etc. Irrigation is mainly carried out by using snow water melted by snow and ice in Tianshan Mountain and Kunlun Mountain. Because the summer temperature is high, the daily range is large, the sunshine is sufficient, the harvest is not low, and the quality is very good. Desert Climate-Classification Sunset Tropical Desert Climate Temperate Desert Climate Subtropical Desert Climate-Tropical Desert Climate English name: The weather is in the tropical desert.

(1) The precipitation is small and the variability is large: Aswin in the Sahara Desert of North Africa has a record of no rain for many years; In Allica, a desert in northern Chile, South America, there have been only three showers that can measure rainfall in a row 17 years, and the total amount of the three showers is only 0.5 1 cm, so the precipitation is very small. Iquiji, also located in the desert of northern Chile, has no rain for four consecutive years, but in the fifth year, a shower dropped by 65,438+05 cm, and in the second year, a shower record reached 63.5cm, showing great variability. Rainfall in tropical deserts is mostly explosive showers, which often cause serious soil erosion. (2) High temperature and large temperature difference: Due to less clouds, strong sunshine, insufficient vegetation coverage and low air humidity, the temperature rises extremely rapidly during the day. It is recorded that the temperature in North Africa is as high as 58℃. Generally, the average monthly temperature in summer is between 30℃ and 35℃, and the high temperature lasts for a long time. For example, in Aden, Arabian Peninsula, the monthly average temperature is above 30℃ for five months in a year. The desert is cooler at night, because there is no cloud all night, and the ground radiation is strong and the heat dissipation is fast. The lowest temperature at night is usually between 7℃ and 12℃, and there are also days of thin frost. The annual temperature difference is generally around 10℃~20℃, and the daily temperature difference is even larger, between 15℃~30℃. At a weather station south of Tripoli in North Africa, 1978,1February 25th, 978, it was recorded that the highest temperature in Jedaias during the day was 37.2℃, but at night, the lowest temperature dropped to -0.6℃, and the daily temperature difference reached 37.8℃, which was really "wearing a fur coat in the morning and wearing yarn in the afternoon".

(3) Strong evaporation and low relative humidity: Tropical desert climate is often cloudless, windy, sunny, high temperature and low relative humidity in Wan Li, so it has strong evaporation. The possible evapotranspiration is 20 times or even about 100 times of precipitation. The relative humidity in the air is very small, and it often appears at about 2% in the Sahara desert of Egypt. The tropical desert climate is mainly distributed in the inland areas where the Tropic of Cancer passes and the west coast of the mainland, with the Sahara desert in northern Africa being the most extensive. Desert climate-temperate desert climate-dry temperate desert climate refers to the climate of desert areas in the hinterland of temperate continent. It is characterized by extreme drought and scarce rainfall, with an average annual rainfall of 200-300mm, and even no rain in some places for many years. It is hot in summer, and the maximum temperature during the day can reach above 50℃; Winter is cold, the average temperature in Leng Yue is below 0℃, and the annual and daily temperature ranges greatly. Less clouds, relatively long sunshine and strong solar radiation. The natural landscape is mostly desert, and there are only a few desert plants in natural plants. Central Asia and Tarim Basin in China belong to typical temperate desert climate. Summary: Temperate desert climate is an extreme case of continental climate. It is the most widely distributed in the subtropical desert. The basic reason is that there is little rain, plants are difficult to survive, and the species and quantity of plants are extremely rare. The ground is bare, the air is very dry and there is little moisture. During the day, the solar radiation is strong, and the ground temperature rises rapidly, and the temperature can reach 60 ~ 70℃. The updraft is strong, but because the air is dry, there are few clouds and little rain, only strong winds and dust. On the ground at night, the temperature drop is extremely strong, even below 0℃. Therefore, the temperature varies greatly every day. Can be as high as above 50 DEG C.. Desert climate-characteristic desert climate-sunrise comes first, rainfall is scarce and the climate is dry. Take the desert area of China as an example. Most of the annual rainfall is below 50- 100 mm, and the least part is below 10 mm. For example, Ruoqiang, located in the southeast of Taklimakan Desert, has an annual rainfall of only 16.9 mm, while Toksun County has even less rainfall, only 5.9 mm. Second, it is windy and dusty. When the wind blows, the sky is full of yellow sand, the sky is dark and the quicksand is everywhere; After the wind stopped, flying sand fell to the ground, forming rows of undulating sand dunes of different sizes. The highest dune can be as high as 400 meters or more. Thirdly, it is hot in Leng Xia in winter, and the annual range and daily range of temperature are very large. For example, in the northwest desert, the average temperature in winter is below -20℃ in 65438+1October, while the average temperature in summer and July is above 26-30℃, and the temperature is as high as 50℃ throughout the year. Compared with annual range, the daily range in desert area is larger. For example, in Turpan Basin, the extreme maximum temperature in summer reaches 82.3℃ during the day, which can be reduced to below 0℃ at night, and the daily temperature difference exceeds 80℃. Therefore, there is a saying in Turpan Basin that "fur coats are worn in the morning, wool is worn in the afternoon, and watermelons are eaten in the same stove". It can be seen that the temperature change of desert climate is the most intense and extreme among all kinds of climate in the world. Desert Climate-The influence of desert climate change near the equator on the west coast of the mainland near the Tropic of Cancer in the southeast of North America and the climate-environment deterioration of inland desert Many observation results show that the global and China climate change has had an important impact on the natural ecosystem and social and economic sectors in China, especially on agricultural production, water supply and demand, forest and grassland ecosystems, coastal areas, etc. These impacts are mainly negative, and some are even irreversible. For China area, since 1950s, the measured runoff of six major rivers in China has shown a downward trend, and some rivers in the north have been cut off, among which Haihe River Basin has the largest decline. At the same time, floods occur frequently in some areas, especially since 1990. The observation also shows that the phenological period in the eastern part of China is advanced, and the northern boundary of subtropical and temperate zones moves northward. Since 1960s, the forest area in Qilian Mountain has decreased by 16.5%, the forest belt has increased by 400m, and the coverage has decreased by 10%. The yield and quality of grassland in Sichuan decreased. The area of wetlands in Northeast China, Qinghai and Southwest China decreased and their functions declined. Climate change also leads to the instability of agricultural production, and the harm of local drought and high temperature increases. Because the development period of crops is advanced after climate warming, the harm of spring frost is increased. Spring drought in Inner Mongolia grassland in China has intensified and productivity has declined. The coastal areas of China are extremely vulnerable to climate change and sea level rise. Extreme weather events such as storm surge, flood and rainstorm, and climate events such as drought are the main causes of disasters in coastal areas. The Yellow River Delta, the Yangtze River Delta and the Pearl River Delta are the most vulnerable. Climate change may have a certain impact on major projects in China. Climate change may increase the precipitation in the upper reaches of the Yangtze River basin and cause geological disasters such as mudslides and landslides in the Three Gorges reservoir area. In the future, the temperature in the Qinghai-Tibet Plateau may become warmer, and the frozen soil along the Qinghai-Tibet Railway will further deteriorate, which will affect the stability of railway subgrade in some sections. At the same time, this global warming will increase the frequency of heavy rain and extreme precipitation events and local floods. In some areas, tornadoes, strong thunderstorms, strong winds and hail will also increase, and many parts of the world will suffer from more frequent, more lasting or more serious droughts. Climate warming makes the temperature in winter higher, which makes all kinds of germs and viruses active, spread pests and diseases, and many harmful animals, such as mosquitoes, fleas and mice, reduce the chance of freezing to death. The number of carriers of such infectious diseases has greatly increased, posing a serious threat to human health. Knowledge about desert climate continental climate in desert areas. Its main features are dry air, little or no rain all year round, drastic daily temperature change, daily range of more than 50℃, the highest ground temperature of 60 ~ 80℃, and rapid cooling at night. Except for a few oases with irrigation conditions, there can only be drought-tolerant plant communities in desert areas, and other plants are almost extinct and even become quicksand or desert. Desert climate can be roughly divided into tropical desert climate and mid-latitude desert climate: ① tropical desert climate. It is mainly distributed on the west side of the continent at about 20 north latitude and 20 south latitude. It's hot in summer and not cold in winter. Because this area has been controlled by subtropical high for a long time, downdraft prevails, atmospheric stratification is stable, and its west coast is often affected by cold ocean currents, which increases the stability of the atmosphere and inhibits the development of convection, so precipitation is scarce. Because precipitation is far less than evaporation, water can't make ends meet for a long time, forming a dry desert climate. Such as the Sahara Desert, Western Australia and Peru. ② Mid-latitude desert climate. Mainly distributed in the hinterland of the central mainland. This kind of area is far away from the ocean, and the humid airflow is difficult to reach, forming an extremely continental climate: hot in summer, cold in winter, and the daily and annual temperature differences are almost the largest in the world, with little or no rain all year round. For example, Taklimakan Desert in Xinjiang, China and Karakum Desert in Central Asia are typical mid-latitude desert climate zones. According to Cobain climate classification, the total area of desert climate accounts for about 12% of the global continental area. Desert climate, long sunshine time and large temperature difference between day and night. In the desert oasis with irrigation conditions, agriculture can obtain high yield and make use of solar energy conditionally. Therefore, with the rapid increase of global population and limited arable land, the utilization of climate resources in desert areas has attracted scientific attention. [ 1]