Why does the polar high pressure area drop less water under the influence of downdraft?

Near the polar regions, the height angle of the sun is the smallest all year round, and it receives the least heat and light from the sun, so it is cold all year round. Air contracts and sinks when it is cold, forming a polar high pressure area. The temperature near the polar regions is low, evaporation is weak, and the water vapor content in the air is low. The downward flow prevails in the polar high pressure control area, so it is more difficult for water vapor in the air to condense, and it is difficult for the air to reach saturation or supersaturation, and it is difficult to form precipitation. Therefore, due to the influence of downdraft in the polar high pressure area, there is little precipitation.

The high pressure belt is controlled all year round, cold and dry. Tundra climate: winter all year round, with little precipitation and obvious extreme day and night. Most of them are distributed in Eurasia and northern North America. The climate is cold all year round, the temperature in the hottest month is between 0~ 10℃, and it is winter all year round. The annual precipitation is below 250 mm, most of which is snow, and some of which can be dissolved in a short time in summer. Relative humidity is high, evaporation is small, and the coast is foggy. Because of the low temperature, trees have disappeared, and only moss and lichen can grow.

Ice field climate: it is cold all year round, with little precipitation and frequent snowstorms. The climate of ice sheet is distributed in Antarctic continent and Greenland plateau, and it is one of the climate types of polar climate zone. It is covered with snow all year round, so it is also called ice desert climate, ice sheet climate or perpetual frost climate. In the hottest month, the temperature is below 0℃, the airflow sinks and the precipitation is scarce. The annual precipitation is about 100 mm.