Tibet, with an average elevation of more than 4,000 meters, is known as the "roof of the world". There are more than 50 peaks above 7000 meters above sea level in China, among which there are 1 1 peaks above 8000 meters above sea level, which is called "the roof of the earth world" except the Antarctic and the Arctic. The whole area is surrounded by Himalayas, Kunlun Mountain and Tanggula Mountain. The landform is complex and diverse, which can be divided into four zones: First, the northern Tibet Plateau, which is located between Kunlun Mountain, Tanggula Mountain and Gangdise-Nyainqentanglha Mountain, is about 2,400 kilometers long and 700 kilometers wide, accounting for 1/3 of the total area of the autonomous region. It is a series of round and gentle hills, with many basins in the middle and lakes that have accumulated water for many years in the lower part. It is the main pastoral area in Tibet. The second is the Southern Tibet Valley, with an average elevation of about 3,500 meters. There are many flat valleys with different widths where the Yarlung Zangbo River and its tributaries flow. The valley is generally 7 to 8 kilometers wide and 70 to 65,438+000 kilometers long. Flat terrain and fertile soil. This is the main agricultural area in Tibet. Third, the alpine valleys in eastern Tibet, namely Hengduan Mountains and Sanjiang Canyon in southeastern Tibet, are a series of alpine valleys that gradually turn from east to west to north and south. The northern part is about 5200 meters above sea level, the top of the mountain is gentle, and the southern part is about 4000 meters above sea level. The mountain is steep, with a drop of up to 2500 meters. The top of the mountain is covered with snow all year round, and the hillside is densely forested. There is a pastoral area with evergreen seasons at the foot of the mountain, and the scenery is strange. Fourth, the Himalayas, distributed in the areas bordering India, Nepal, Bhutan, Sikkim and other countries, are the highest mountains in the world, with an average elevation of about 6,000 meters. The western mountainous area has high altitude, dry and cold climate, mild climate in the east, abundant rainfall and dense forests.

Tibet's climate is unique, complex and diverse, generally characterized by cold northwest, warm and humid southeast, and zonal distribution from southeast to northwest, namely: subtropical-temperate-sub-temperate-sub-frigid zone-frigid zone; Wet-semi-humid-semi-arid-drought. Due to the complex terrain, diverse regional climate and obvious vertical climate zone. The climate in Tibet is characterized by long sunshine hours and strong radiation; Low temperature and large temperature difference; Wet and dry, rainy night; Dry in winter and spring, windy; Low air pressure and low oxygen content.

Because of its high altitude, thin air, low water vapor and dust content and low latitude, Tibet's total solar radiation is the largest in the country, and sunshine hours are also the high-value center in the country, showing the characteristics of gradually increasing from southeast Tibet to northwest Tibet. The annual variation of solar radiation is the smallest in 1 month and the largest in June or July. The annual average sunshine hours in the whole region are between1.620 ~ 3,400 hours, and as high as 3,000 ~ 3,400 hours in the western region. The average temperature in Tibet gradually decreases from southeast to northwest, and the annual average temperature in the whole region is between -2.8℃ and 1 1.9℃, with a large temperature difference. The average annual temperature in the warmest southeast region is about 10℃, the average annual temperature in the Yarlung Zangbo River valley region is between 5℃ and 9℃, the average monthly temperature in the eastern Hengduan Mountain region is above 10℃ for about five months, the average annual temperature in the northern Tibet Plateau is below 0℃, and the average annual temperature in the Himalayas and its northern foot is below 0℃. %