What are the climatic characteristics of plateau alpine climate?

Climatic characteristics of plateau and mountain areas

The simplest feature: extremely cold, obvious vertical difference.

(Because the atmospheric temperature in the troposphere decreases with the elevation,) The plateau is high in altitude and the climate is dry and cold; With the change of altitude, the vertical climate difference between plateau edge and mountain area is obvious.

Specific analysis:

① Atmospheric pressure decreases exponentially with the elevation. Under clear skies, the direct radiation intensity and effective radiation intensity of the sun at night in snow-free mountainous areas increase with the increase of height. 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 the direction and slope of the mountain range on the temperature is mainly manifested in the difference of the temperature on both sides of the mountain range, which leads to different climate phenomena. The sunny slope has a high temperature and a large change, while the shady slope has a low temperature and a small change. The daily difference between the mountain top and the hillside is relatively smaller than that in annual range, and the temperature in autumn is higher than that in spring. The daily range of valleys and mountain basins is relatively larger than that of annual range, and the temperature in spring is higher than that in autumn.

(3) Precipitation and precipitation days increase with the increase of altitude. In mountainous areas above a certain height, precipitation decreases with the increase of height because of the decrease of water vapor content in airflow. 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 windward side and desert or semi-desert landscape on the east side of leeward side. Mountain topography also affects the daily variation of rainfall. Generally, it rains mainly at the top of the mountain during the day, and it rains mainly at night in the valley basin.

④ The wind speed increases with the elevation in mountainous areas. The wind speed at the top of the mountain, the ridge and the canyon is higher, while the wind speed at the basin, the valley bottom and the leeward side is lower. Generally, the wind speed in high mountains is high at night, small during the day and minimum in the afternoon, but the opposite is true in foothills and valleys. Mountain areas can also produce some local circulation, such as valley wind, Bula wind, foehn wind, slope wind, glacier wind and so on.

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 alpine areas in winter, with less clouds and less relative humidity at the top of the mountain in winter. The relative humidity of valleys and basins changes greatly from day to day, with high night and low day, and the lowest in the afternoon. The diurnal variation of relative humidity at the top of the mountain is generally small.

Detailed characteristics of plateau mountain climate

(1) The differentiation of vertical climatic zones in mountainous areas is different due to the latitude of the location and the height difference of the mountain itself. In low latitude mountainous areas, the climate at the foot of the mountain is equatorial or tropical. With the increase of altitude, the surface heat and water conditions change gradually, and vertical climatic zones appear alternately. This change is similar to the change of lowlands with the increase of latitude. The higher the latitude of the mountain, the smaller the differentiation of the vertical climate zone. The difference of altitude in mountainous areas is small, and the differentiation of vertical climate zone is small.

(2) The vertical climate zone in mountainous areas has the "brand" of local climate types. For example, the equatorial mountain area has the characteristics of no obvious change from the foothills to the top of the mountain all year round. Both Mount Everest and Changbai Mountain have monsoon climate characteristics.

(3) The differentiation of mountain vertical climate in humid climate zone is mainly determined by heat conditions, while the differentiation of mountain vertical climate in arid and semi-arid climate zone is closely related to heat and humid conditions. The dryness in this area is greater at the foot of the mountain, and gradually decreases with the elevation.

(4) In the same mountainous area, due to the different local conditions such as slope direction, slope, topographic relief, concave and convex, looming, the vertical change of climate is also different, such as the warm zone on the hillside and the cold lake in the valley. There is indeed a change in the climate in mountainous areas.

(5) Vertical climatic zones in mountainous areas have different origins and characteristics from horizontal climatic zones with different latitudes.