Climatic origin of Siberia

2. Winter is the center of continental cold high pressure, which is easily affected by polar cold air flow.

Most parts of Siberia belong to the sub-cold zone coniferous forest climate.

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Winter is long and cold, and the average monthly temperature is below 0℃. Summer is short and warm, the monthly average temperature is above 10℃, and the annual precipitation is 300 ~ 600 mm Due to weak evaporation, the relative humidity is high. The temperature is the highest all year round. This is because this area is the source of polar continental air mass, with high latitude, long night time in winter, small solar altitude angle at noon, snow and strong ground radiation cooling, which is beyond the adjustment of ocean air mass. It extends from east to west into a wide and narrow strip. Because of its high latitude, the winter is long and cold. The warm season is short, and the temperature is particularly high all year round. Summer precipitation is scarce and concentrated, but the temperature is low, evaporation is weak and relative humidity is high. Natural vegetation is coniferous forest.

Climatic characteristics of central Siberia

Most of central Siberia is located in the northeast of the Asian continent, with 30 degrees north latitude and high terrain. The west is far from the Atlantic Ocean, and the east is close to the Pacific Ocean, but the east and south are separated by mountains and are not affected by the ocean. Only the north is open to the Arctic Ocean. Therefore, the climate in this area is characterized by strong continental degree and less precipitation, which is even worse than Siberia, and it is an extremely bad continental climate.

In winter, the surface temperature drops strongly in this area, and the amount of solar radiation is very small, with an average of 80 kcal/cm2 per year, and the air pressure is very high. The whole area is basically controlled by the ice ocean air mass and the dry and cold air mass of Siberia in the polar region. The temperature is very low in winter, with the average temperature of -20 ~-27℃ in June and -43 ~-50℃ in the north (the temperature can drop to -60 ~-68℃ in the coldest days). The average temperature in June 65438+ 10 in this area is 6 ~ 14℃ higher than that in other areas at the same latitude. The inversion caused by cooling during radiation can reach more than 1000 meters, and some mountain basins and valleys are more conducive to the inversion of temperature.

Located in the northeast of this region, the Yansk (located in the middle reaches of the Yana River at an altitude of120m) and the Oymyakan (located in the upper reaches of the Gandijika River) regions in the northeast of Siberia are located in the valley on the north side of the huge Yansk-Kolemayama arc, surrounded by mountains on the east, west and south, which is particularly conducive to the invasion, sinking and detention of ice air masses and cold air. In addition, it is located at high latitudes. Known as the "cold pole" in the northern hemisphere, Oymyakon (the absolute minimum temperature is -7 1 LUN) and Yogyakask (-68℃) are known as the "two daughters of the cold pole". There are abundant cyclones in winter, and there is almost no cyclone activity. It is partly cloudy and sunny, with little precipitation, which is 3o ~ 150mm, accounting for only 15-25% of the annual precipitation.

The summer temperature in central Siberia is relatively high. The average temperature in July is generally 14 ~ 16℃, but it can exceed 20℃ in some southern areas, and the daily average temperature can reach 1 1 ~ 35℃. Even Oyimyakan measured the absolute maximum temperature of 32℃. There is more precipitation in warm season, accounting for 75 ~ 80% of the annual precipitation.

The annual precipitation in this area is less than that in western Siberia. Except for the narrow areas along the Yenisei River basin in the east and the mountainous areas in southern Siberia, the annual precipitation is generally below 465,438+065,438+0mm, and even less in the "cold pole" areas. The annual precipitation is scarce, the annual fluctuation is large, and the continental degree is large (the continental degree of eastern Siberia is above 80%), which shows that eastern Siberia has the strongest continental climate in Asia.

The extremely cold continental climate leads to the widespread distribution of frozen soil in this area. The frozen soil in the north is as deep as 500 ~ 600 meters, and in some places it even reaches 800 ~ 1500 meters. Parameter The thickness of permafrost in mountainous area is 200 ~ 400 meters. Frozen soil is also distributed in alpine areas such as Altai in southern Siberia, modern glaciers are developed, and underground ice can be seen everywhere in low plains. In the Szantal-Hayata Mountains and Chersky Mountains in this area, the total area of mountain glaciers exceeds 3.8 million square kilometers, the height of snow line is 265,438+000 ~ 2,600 meters, and the glacier tongue can extend to 800 ~ 2,000 meters.

Because of the high mountains in this area, the vertical zonal change of climate is also obvious, especially in the mountainous areas of southern Siberia. For example, the annual cement drop in the foothills is only 300 ~ 400 mm, but the precipitation of 2000 ~ 2500 meters can be increased to 700 ~1000 mm.