Causes and characteristics of subtropical monsoon climate
Climatic Causes The subtropical monsoon climate is formed because it is located near the Tropic of Cancer, and most of the subtropical monsoon climate is located north of the Tropic of Cancer, which is mainly caused by the difference in thermal properties between land and sea. Because it is located on the coast, it is influenced by the temperature difference between land and sea in summer, and it blows southeast wind, and in winter it is influenced by the cold wind from Siberia, and it blows northwest wind. The two control alternately and change seasonally, forming monsoon.
The subtropical monsoon climate is distributed on the east coast of the mainland at 25 ~ 35 north latitude, and it is a zone where tropical marine air masses and polar continental air masses alternately control and compete with each other. It is mainly distributed in the south of Huaihe River in Qinling Mountains in eastern China, north of tropical monsoon climate, south of Japan and south of Korean Peninsula. It's not cold here in winter. The average temperature in 65438+ 10 is generally above 0℃, and it is hot in summer. The average temperature in July is generally around 25℃, and the direction of Xia Feng changes obviously in winter. The annual precipitation is generally above 1000 mm, and may be above 1300 when the humid monsoon is active. Mainly concentrated in summer, less in winter. This climate is most typical in the southeast of China. In other areas, because there is a considerable amount of precipitation in winter, there is little difference between winter and summer, so it is called subtropical monsoon humid climate.
Climate characteristics: The subtropical monsoon climate zone is rich in heat resources, with the annual average temperature ranging from 13℃ to 20℃, ≥/kloc-0℃ ... 65438+10. The monthly average temperature is above 0℃, 0℃2' in the north of the Yangtze River and 2C~ 10 in the south of the Yangtze River. Due to the low terrain and weak barrier function, Huaiyang Mountain is often affected by cold air from the south in winter, especially Jianghan Plain and Dongting Lake Plain, which are connected to Nanyang Basin in the north and Gui Xiang Corridor in Nantong. Winter becomes a channel for cold air to move southward, where the 65438+ 10 monthly isotherm protrudes southward in a tongue shape. The absolute minimum temperature in the north of the Yangtze River can reach below-10'C, and Hankou once appeared-18. The lowest value 1C (1977 65438+1October 30th) is between -7c and1c in the south of the Yangtze River. Whenever strong cold air goes south, the temperature drop can often exceed 10' C, and the temperature drop in Shanghai is 25 in two days. 2C record.
Therefore, although this area is subtropical, the winter temperature is lower than other parts of the world at the same latitude. Due to the low temperature in winter, the subtropical latitude of China is south, and its northern boundary is 4~5 latitudes south than the theoretical boundary. Compared with the Mediterranean region, it is 10~ 1 1 latitude to the south. However, the subtropical areas of China, especially Central China, are generally hot in summer, with the average temperature reaching about 28℃ in July and exceeding 29℃ in some areas. High temperature weather far away from 35℃ often occurs from May to September. July-August is controlled by subtropical high, with sunny days and long sunshine hours, with the highest frequency of high temperature, and the absolute high temperature often exceeds 4 4' C. Jinhua, Lishui, Zhejiang and Anhua, Hunan all have meteorological records of high temperature above 465,438+0' C, and the average temperature in April and 10 is16 * c 2/kl.
The average annual precipitation in the subtropical monsoon climate zone is generally 800mm~ 1600mm, which is twice as much as that in North China and richer than that in Southwest China. The distribution of precipitation decreases from southeast to northwest. The annual precipitation in hilly areas of Zhejiang Province is 1200mm~2000mm, that in hilly areas of Nanling and Jiangnan is about 1500mm, and that in plain areas of the middle and lower reaches of the Yangtze River is1000 mm ~1200 mm.. The influence of topography on precipitation is also remarkable. Generally, there are more mountains than flat land, and there are more windward slopes than leeward slopes. For example, Tunxi in Anhui is very close to Huangshan, and the precipitation in Huangshan is 700mm more than Tunxi (Tunxi 1507. 8mm, Huangshan 2263. 9 mm). The annual precipitation of Luoxiao Mountain and Xuefeng Mountain can exceed 180cm.
In the seasonal distribution of precipitation, summer rain is the most, followed by spring rain, autumn rain is worse, and winter rain is the least, but winter rainfall can also account for more than 10% of the annual precipitation.