What are the characteristics of subtropical monsoon mountain climate?

The subtropical monsoon climate is distributed on the east coast of subtropical continent with latitude of 25 ~ 35, which is a zone where tropical marine air mass and polar continental air mass 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 is not cold in winter, and the average temperature in 65438+ 10 is generally above 0℃, and it is hot in summer, and the average temperature in July is generally 25℃. In winter, the direction of Xia Feng changes obviously, and the annual precipitation is generally above 1 000mm, which is mainly concentrated in summer and less in winter. This climate is most typical in the southeast of China. Other areas are called subtropical monsoon humid climate because there is also a considerable amount of precipitation in winter, and there is little difference between winter and summer.

This area is located between 25 and 35 north latitude and is divided according to the climate of planetary wind system. This is an arid area controlled by subtropical high. However, due to the difference between land and sea and the change of temperature and pressure field caused by the uplift of the Qinghai-Tibet Plateau, the monsoon circulation changed the circulation system of the near-surface planetary wind system, from the arid continental climate to the humid subtropical monsoon climate, and from the arid desert landscape to the humid evergreen broad-leaved forest landscape. After thousands of years of human activities, this area has become a densely populated area in China.

The climate in this area is characterized by warm winter and hot summer, distinct four seasons, abundant precipitation and even seasonal distribution.

The area is rich in heat resources, with the annual average temperature ranging from 13℃ to 20℃ and the accumulated temperature ≥ 10℃ ranging from 4000℃ to 6500℃. The average monthly temperature in 65438+ 10 is above 0℃, 0℃~2℃ north of the Yangtze River and 2℃~ 10℃ south of the Yangtze River. Winter is often affected by the cold air from the south, especially Jianghan Plain and Dongting Lake Plain, which are adjacent 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℃. The lowest value-18. 1℃ once appeared in Hankou (1977 1.30), and it was mostly between -7℃ and-10℃ in the south of the Yangtze River. Whenever strong cold air goes south, the temperature often drops above 10℃. However, the temperature in winter is lower than that in other parts of the world at the same latitude. Due to the low temperature in winter, China's subtropical zone is located in the south, and its northern boundary is 4~5 latitudes lower than the theoretical boundary. Compared with the Mediterranean region, south latitude 10~ 1 1. China's subtropical zone, especially central China, is generally hot in summer, with an average temperature of 28 in July. In some areas, when the temperature exceeds 29℃, high temperature weather above 35℃ often occurs from May to September. July-August is controlled by subtropical high, with many sunny days, long sunshine hours, the highest frequency of high temperature, and the absolute high temperature often exceeds 40℃. High temperatures above 465 and 438+0℃ were recorded in Jinhua, Zhejiang and Anhua, Hunan. April and June, 10.

Generally speaking, the middle and lower reaches of the Yangtze River are warm in winter and hot in summer, with four distinct seasons. Generally, winter is 1 ~ April, 4 months north of the Yangtze River, and less than1month in Nanling area. Summer lasts for more than four months, generally ending from mid-late May to late September, and arriving at the beginning of 10 at the latest in the south. In most areas, it lasts for two months in spring and autumn, and it can last for three months in the south.

The average annual precipitation in this area is generally 800.

Mm~ 1600 mm, more than North China 1~2 times, richer than Southwest China. The distribution of precipitation decreases from southeast to northwest. Annual precipitation in hilly areas of Zhejiang province 1200 mm~ 1800.

Mm, Nanling Mountain and Jiangnan Hill are about 1500 mm, and the middle and lower reaches of the Yangtze River are 1000mm ~ 1200mm.

Terrain also has a great influence on precipitation. Generally, mountainous areas are more than flat land, and windward slopes are more than leeward slopes. For example, Tunxi in Anhui is very close to Huangshan, and the precipitation in Huangshan is 700 more than Tunxi.

Mm (Tunxi 1507.8 mm, Huangshan 2263.9 mm). The annual precipitation of Luoxiao Mountain and Xuefeng Mountain can exceed 1800 mm.

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. The middle and lower reaches of the Yangtze River are the areas with the highest proportion of winter rain and the richest spring rain in China.

This seasonal distribution of precipitation is closely related to the geographical location of the middle and lower reaches of the Yangtze River and the atmospheric circulation process.

The middle and lower reaches of the Yangtze River lie in the east of the Qinghai-Tibet Plateau. In winter, the north-south jet of the westerly belt meets over this area, forming a relatively stable shear line. Coupled with the influence of Nanling Mountains, a quasi-static front of South China appears on the ground for a relatively long time, with frequent cyclones and extremely rainy weather. June 5438+February and June 5438+1October, the average precipitation in most areas is 40.

February Mm~50 mm, 60 mm~80.

Since about mm months, the warm and humid air flow in the south has been strengthened and the precipitation frequency has increased. In late March, Gannan first entered the spring rain period, with this as the center, the spring rain gradually extended to the northwest, southwest and northeast (figure 12. 1.2). In most areas, the spring rain didn't end until early and middle June. There is more precipitation in spring and longer rainy period in hilly areas of the south of the Yangtze River. The rainy season lasts 60 days. There are many spring rains in this area, and the proportion of spring rains in Changsha and Nanchang is about 40%, which is more than summer rain. In Nanjing, Shanghai and Wenzhou, spring rain accounts for about 25% of the annual precipitation.

mountain climate

mountain climate

The local climate affected by altitude and mountain topography. The main influencing factors are altitude, mountain situation, slope direction and topography.

Main features of mountain climate:

① Atmospheric pressure decreases exponentially with altitude. Under clear skies, the direct radiation intensity and effective radiation intensity of the sun at night in snow-free mountainous areas increase with the elevation. Because of the different slope directions, the solar radiation obtained by sunny slope and shady slope is different, which affects the distribution of air temperature and airflow.

② The temperature decreases with the elevation. Generally speaking, the vertical drop rate of temperature is the largest in summer and the smallest in winter. The influence of mountain range and slope direction on temperature is mainly manifested in the difference of temperature on both sides of mountain range, which leads to different climate phenomena. The sunny slope temperature is high, and the shady slope temperature is low, with little change. The daily temperature difference between the top of the mountain and the hillside is relatively smaller than that in annual range, and the temperature in autumn is higher than that in spring. The daily temperature range in valleys and mountain basins is relatively larger than that in annual range.

(3) The precipitation and precipitation days in mountainous areas increase with the elevation. In mountainous areas above a certain height, due to the decrease of water vapor content in airflow, precipitation decreases with the increase of altitude. The height at which precipitation reaches the maximum is called the maximum precipitation height. The influence of slope direction on rainfall is that the rainfall on windward slope is greater than that on leeward slope. Especially on both sides of the tall mountains, the huge difference in rainfall causes great changes in vegetation landscape. For example, the Cordillera mountain system in the south-central part of the west coast of North America is located in the temperate westerly belt, with forest landscape on the west side of the windward and desert or semi-desert landscape on the east side of the leeward. Mountain topography also affects the daily variation of rainfall. Generally speaking, there is more daily rain at the top of the mountain range, while there is mainly night rain in the valley basin.

④ The wind speed increases with the elevation of the mountain. The wind speed at the top of the mountain, the ridge and the mouth of the canyon is higher, while the wind speed at the basin, the valley bottom and the leeward side is lower. Generally, the wind speed on the mountain is high at night, small during the day and minimum in the afternoon, but the opposite is true in the foothills and valleys. Mountains can also produce some local circulation, such as valley wind, mine-laying wind, foehn wind, slope wind and glacier wind (see local wind).

⑤ In terms of humidity (water vapor pressure and relative humidity), the water pressure decreases with the elevation. In most cases, the relative humidity of the upper part of the mountain is higher than that of the lower part of the mountain because of the low temperature and more clouds, but it is also the opposite in the alpine area in winter, with less clouds and less relative humidity at the top of the mountain in winter. The relative humidity in valleys and basins varies greatly from day to day, which is high at night, low during the day and lowest in the afternoon. The diurnal variation of relative humidity at the top of the mountain is generally small.