Weather characteristics of Saudi Arabia

Subtropical Arid and Semi-arid Climate Zone (Saudi Arabia) It is a subtropical arid and semi-arid climate from Arabian Peninsula to thar desert in the lower reaches of the Indus River. Because a large area of land here is under the control of subtropical high, there are mountain plateaus and basins on the ground, which also contributes to the formation and development of desert climate. It's hot in summer and cold in winter here. For example, the temperature in Baghdad can reach 49℃ in summer, and the lowest temperature in winter is -8℃. Karachi is 48℃ in summer and 4℃ in winter. To the east of thar desert, the distribution of subtropical arid climate is gradually interrupted by monsoon. The subtropical region of Asia is similar to southern Africa, and the terrain is not as flat as that of North Africa, and the uneven terrain in the east also prevents the arid climate from spreading eastward in a large area. Tropical continental air mass (Tc) spreading eastward from the southern edge of Iranian low pressure prevails in Hutart desert, which prevents equatorial monsoon air flow (Em) from reaching the north. In addition, the vertical thickness of southwest monsoon at its northern boundary is not thick; In addition, the high altitude in this area is anticyclone in summer, and the low altitude is marked by heat and low pressure, which is not easy to cause rainfall, so the precipitation here is scarce, only about 75 ~ 150 mm, forming a desert. The Iranian plateau is mainly an intermountain plateau and basin surrounded by marginal mountains. Summer is not as hot as India and Arabia, and winter is not as cold as Central Asia. Climate has the nature of transition from temperate arid area to tropical arid area. The temperature in the plateau is mostly 5 ~ 10℃ in winter, and it can reach 30 ~ 32℃ in the southern lowlands in summer, and the highest can reach 40 ~ 50℃. Because the western part of this area is adjacent to the Mediterranean climate zone, there is some precipitation in winter and spring, and the rainfall in the west is more than that in the east. The annual precipitation on the southwest slope of zagros mountains and the north slope of Elbers Mountains is 500mm, but the internal precipitation is less than 100mm.

(2) Tropical arid and semi-arid climate zone (tropical desert and semi-desert climate zone) This area is located on the southern edge of Arabian Peninsula and Iranian Plateau, and is an eastward extension of the desert belt in North Africa. Due to the influence of subtropical high and northeast trade winds, the climate is very dry and hot. The average temperature in the hottest month is 30 ~ 39℃, the average temperature in Leng Yue is 10 ~ 25℃, the absolute maximum temperature is above 55℃, sometimes it drops to 0℃ at night, the annual range is generally below 18℃, and the daily range can sometimes reach 35 ~ 40. Due to the lack of humid southwest monsoon, precipitation in this area is scarce, and some have not dropped a drop of rain in the desert for many years (but there is also a record of a rainstorm with a precipitation of tens of millimeters), so tropical deserts are widely distributed. The main difference between tropical desert area and temperate desert area is that the former is hot in summer and not cold in winter, which is a typical dry-hot climate with frequent sandstorms, accompanied by high temperature and very dry air (relative humidity is 10%).

Pan-arid climate, that is, desert climate, is dominated by zonality without latitude. Although temperate, subtropical and tropical semi-arid climates can be divided from north to south in temperature, except for a few cases, they are continuous in regional distribution and difficult to distinguish. The distribution of global arid areas is mainly concentrated in the northern hemisphere north latitude 10 ~ 50 and the southern hemisphere south latitude 15 ~ 50. The arid areas near the equator are mainly distributed in the coastal areas of Peru in South America, northeastern Brazil in East Africa, Kenya, Ethiopia and Somalia. The most widely distributed arid area in the world is the west coast of North Africa-Sahara-Arabian Peninsula-Iran-Central Asia, which is 13000 km long from east to west. Subtropical and tropical deserts can be collectively called hot deserts. Their common feature is strong sunshine. The annual sunshine hours are 3500-4000 hours, the relative humidity is lower than 50%, the annual average temperature is higher than 65438 08℃, and in some places it is above 25℃, and the surface temperature can reach 80℃, but it can be as low as 0℃ at night. The average temperature in Leng Yue is not lower than 18℃, and the annual range is not high, which is around 18℃. The daily range is quite large, reaching 35 ~ 40℃, with little precipitation, generally less than 250 mm, and less than 100 mm in some places, even without dripping for several years, and sandstorms often occur. Temperate desert is a cold desert, characterized by cold winter, extreme temperature difference of 90℃, average temperature of 3 ~- 10℃ in Leng Yue and about 50℃ in summer under the shade of trees. In the northern hemisphere, temperate deserts are related to vast land area and being far away from the ocean, while subtropical and tropical deserts are controlled by subtropical high belts.

(3) Subtropical summer arid climate zone (Mediterranean climate zone) This area is mainly located in Asia Minor Peninsula (except inland), Mediterranean coastal area and the western edge of Iranian plateau. Compared with the monsoon region of the same latitude on the east coast of the mainland, the climate characteristics are obviously different. It belongs to the subtropical climate on the west coast of the mainland, with abundant sunshine in summer, hot and dry, and mild and rainy in winter.