Basic characteristics of mountainous climate in my country
Among the climate factors that have the greatest impact on the formation of geological disasters are temperature, precipitation and evaporation.
1.1.1 Precipitation
my country is bordered by the Pacific Ocean to the east and south, and not far from the Indian Ocean to the southwest. These two oceans are the main sources of water vapor for precipitation in my country. In addition, the water vapor brought by the northerly airflow from the Arctic Ocean also plays a certain role in the precipitation in northern Xinjiang, my country.
The general trend of annual precipitation distribution in my country is that it gradually decreases from the southeastern coast to the northwest inland. The isoprecipitation lines roughly run from northeast to south-west and can be roughly divided into three zones. Bounded by the Greater Hinggan Mountains, Yinshan Mountains, Helan Mountains, Bayan Hara Mountains, and Gangdese Mountains, the vast area to the west and north of this line has an arid climate, with annual precipitation roughly below 200mm, except for some high mountain areas with slightly more precipitation. The area east and south of this line to the southeast of the Qinghai-Tibet Plateau - eastern Qinghai - southern Gansu - the southern slope of the Qinling Mountains - north of the Huaihe River and the Shandong Peninsula line, except for the Changbai Mountains in the northeast and the Greater and Lesser Khingan Mountains, are all semi-arid, In semi-humid climate areas, the precipitation is roughly between 200 and 800mm. The vast area south of this line is a humid area, with precipitation generally greater than 800mm.
In mountainous areas with heavy rainfall or concentrated rainfall, there are more adverse physical geological effects and geological disasters. In arid climate areas, continental salinization is intense, groundwater has high salinity properties, and its water quality is often corrosive.
1.1.2 Temperature
Temperature distribution is obviously affected by geographical latitude, sea and land distribution and terrain fluctuations. my country spans a large latitude and has a large temperature difference between north and south. In terms of annual average temperature, from above 25℃ in the South China Sea Islands to below -5℃ in northern Heilongjiang Province, the difference is more than 30℃. Its distribution gradually decreases with increasing latitude from south to north in the eastern half. The temperature south of Nanling is above 20°C, the Yangtze River Basin is around 16°C, the Yellow River Basin is 12°C to 14°C, and the entire Northeast and Inner Mongolia are above 10°C. Below 0℃, the Greater and Lesser Khingan Mountains are below 0℃. Due to the influence of terrain uplift in the western half, the annual average temperature in most areas of the Qinghai-Tibet Plateau is below 0°C, with the lowest temperature in northern Tibet being below -8°C. In Xinjiang to the north, except for the Tianshan and Altai Mountains, the temperature is above 0°C. , most areas of the Tarim Basin and Turpan Basin in southern Xinjiang are above 10°C.
The influence of temperature on environmental geological conditions is very obvious. In low-temperature areas, such as the Qinghai-Tibet Plateau and northern Heilongjiang, permafrost is distributed, and freeze-thaw physical geological phenomena develop. In hot and humid areas, rock and soil weathering is intense. Due to seasonal changes in temperature, seasonal frozen soil appears in cold areas in winter, and geological disasters such as freezing and thawing often occur.
1.1.3 my country’s climate zonal patterns
The cooperation of various climate elements and weather phenomena in different seasons results in different climate distribution characteristics in various places. This climate characteristics also affects Other natural factors in nature such as vegetation, soil, landforms, etc. play a huge role, and these natural factors, in turn, affect the local climate. According to my country's natural landscape, the country can be divided into three major regions, namely: the eastern monsoon region, the northwest arid region and the Qinghai-Tibet Plateau region.
The eastern monsoon area extends from the north of Heilongjiang Province to the South China Sea Islands. Affected by the alternation of monsoons during the year, the wind direction has obvious seasonal changes. The difference in temperature between north and south is small in summer and large in winter. Precipitation is concentrated in the warmer second half of the year.
The northwest arid region accounts for about 30% of the country's total land area. Its main characteristics are less precipitation throughout the year, warm or even hot summers, and cold winters. And because the air is dry and evaporation is large, the area is mostly desert and grassland.
The climate of the Qinghai-Tibet Plateau is severely cold and can only be divided into warm season and cold season, with obvious vertical zoning around it. The freezing period in permafrost areas lasts for more than 7 months. The average temperature on the plateau is below -2℃~6℃, the annual temperature range is 15℃~26℃, and the average daily temperature range can reach 10℃~19℃; the annual precipitation in the permafrost area in the northern part of the plateau is about 300mm; the Yarlung Zangbo River Valley It increases to more than 400mm; the precipitation in southeastern Tibet is 500~800mm; the precipitation in the western part of the plateau is less than 100mm.
Under the background conditions of the above three major regions, different temperature zones can also be divided according to the temperature difference between the north and the south. In addition to the Tibetan Plateau, it can be divided into three major zones: temperate zone, subtropical zone, and tropical zone. The dividing line between the temperate zone and the subtropical zone is roughly along the Huaihe River and the Qinling Mountains. The dividing line between the subtropical zone and the tropical zone passes through the southern part of Taiwan Province, the northern end of Leizhou Peninsula in Guangdong Province and the southern part of Yunnan Province.