Characteristics of polar meteorology

Most of the Arctic region is a sea surrounded by Eurasia and North America, with an area of about 1 365,438+10,000 square kilometers. Most of the Antarctic region is a continent surrounded by oceans, covering an area of about 6,543,800 square kilometers. The average height of the Antarctic continent is about 2350 meters, including more than 3000 meters, accounting for about 25% of the Antarctic continent area, and the highest is about 4000 meters. The temperature difference between the center and the edge of the mainland is very large, with an average difference of about 30℃, which can reach 55℃ in April. The temperature difference in the Arctic is not big, generally not more than 10℃ ... Both polar regions are ice regions, and the average ice boundary in the Arctic is about 72 degrees north latitude and 63 degrees south latitude. The ice and snow in the Arctic can melt a lot in summer, while 97% of the Antarctic continent is covered with ice all year round, with an average thickness of 1700 meters, which generally does not melt. The sea ice area around the Antarctic continent changes greatly: the sea ice area is the smallest in March, about 5 million square kilometers, and the ice boundary is about 70 south latitude; The ice area is the largest in September, about 2000.

10 thousand square kilometers, the ice world is about 57 south latitude. These characteristics affect the radiation of the north and south poles, the wind system near the surface and the temperature distribution. The year-round cold climate of the earth's north and south poles. Its range varies with different climate classification methods. Astronomical classification takes the climate of Antarctic circle (66 33' ~ 90 south latitude) and Arctic circle (66 33' ~ 90 north latitude) as polar climate; The air masses are classified as polar climate with the climate from the North Pole Front to the North Pole and from the South Pole Front to the South Pole. According to the classification rules of climatic factors and natural landscapes, the climate in high latitudes where the average temperature in the warmest month is lower than 10℃ and trees cannot grow is polar.

The polar climate has the following main characteristics:

① The annual radiation difference is negative. In any season, the underlying surface is colder than air, thus forming a stable Arctic air mass and Antarctic air mass.

(2) There are extreme days and nights, the longest of which is half a year. Although the extreme daytime is long, the temperature is low because of the small altitude angle of the sun, weak illumination and strong snow reflection.

(3) The evaporation is small, and the water vapor that produces precipitation is foreign. Precipitation appears in the form of snow, which is small in quantity, low in temperature and difficult to melt. It has accumulated for many years and formed a thick continental ice sheet.

(4) The wind and snow are dry, the visibility is poor, and the extreme day is foggy along the coast. There are two types of polar climate:

(1) tundra climate. ET climate is equivalent to Coburn climate classification. The average temperature in the warmest month is lower than 10℃, but higher than 0℃. The average monthly temperature is above 0℃ only for 2 ~ 4 months in a year. There are plants such as moss and lichen growing. Siberia, Alaska, Canada's Arctic Ocean coast and adjacent islands, as well as Greenland's narrow coastal zone all belong to this climate.

② tundra climate. EF climate is equivalent to the classification of Keben climate. The temperature is below 0℃ all the year round, and the ice and snow will not melt for many years. The Antarctic continent, most of Greenland and the central Arctic Ocean all belong to this climate.