What is the climate like in Tibet?

Because most parts of Tibet are above 4000 meters above sea level, the climate is extremely cold, strictly speaking, there is no summer, only long winter and spring and autumn, and there are many characteristics in the climate:

(1) The air is thin, with low oxygen content and low air pressure. The plateau air is thin, and the air density is mostly 0? 7 1—0? 80 kg/m, about 60%-70% of the air density at sea level; The oxygen content is below sea level.

35%—40%; The air pressure is only half of the sea level. The boiling point of water also dropped to about 84-87℃. Due to the low air pressure, thin air and low oxygen content in the plateau, people who come to the plateau for the first time often have altitude sickness such as headache, chest tightness, rapid heartbeat, asthma and dyspnea. Generally, after a certain period of adaptation, altitude sickness will gradually ease or disappear. ?

(2) Sufficient illumination and large radiation. Because of the high altitude, thin and clean air, low dust and water vapor content and good atmospheric transparency, the loss of solar radiation is less when sunlight passes through the atmosphere, which is the area with the most solar radiation in China. The annual total radiation in most parts of Tibet is above 160 kcal/cm, and that in Lhasa is 19 1 kcal/cm, especially in Dingri and Bango, where the annual total radiation exceeds 200 kcal/cm, almost twice as much as that in the coastal areas of the mainland. The average sunshine hours in Tibet are between 1550-3390 hours, and Lhasa is 3005 hours, which is known as the "Sunshine City". Sufficient light and light energy in Ying Da provide broad prospects for the development of agriculture, forestry and animal husbandry. The upper limit of agriculture, forestry and animal husbandry set a world record. For example, the upper limit of highland barley planting has reached a record of 4750 meters. The distribution of natural forests reached a record 4400 meters, and the consumption of grazing grassland and cattle reached the highest records of 5500 meters and 6000 meters respectively. ?

(3) When the temperature is low, the annual change of the temperature is small and the daily change is large. The annual average temperature in the northern Tibetan plateau is about -2℃, 8℃ in the southern Tibetan valley and 10℃ in the southeast Tibet. The temperature distribution law is roughly that the temperature drops by 6℃ every 1000m, so the temperature in Tibet is roughly 20℃ lower than that in the eastern part of the same latitude. Because it is not too cold in winter and not too high in summer, the temperature difference is not big throughout the year, but the temperature changes greatly every day, and many places are above 30℃. People often use "there are no four seasons in a year, and four seasons are seen in one day" to describe the plateau climate characteristics with small annual and large daily changes in temperature. The plateau has high daytime temperature, long photosynthesis time, low temperature and low respiratory consumption, which is beneficial to the accumulation of photosynthetic products. Therefore, the 1000-grain weight of rose crops planted in the plateau is as high as 56 grams, while that in the eastern region of the same latitude is only over 30 grams. Rhizome crops are large, and the potato yield per mu can reach 15000 kg. One radish weighs more than 30 kilograms, and the other lotus white one weighs more than 40 kilograms.