It snows in the south. Why does it not snow in Beijing?

Xinhua News Agency, Beijing, 65438+1October 7th-Since the early morning of the 7th, there has been a little snowfall in Fangshan and Yanqing, the outer suburbs of Beijing. However, the "Mao Mao Snow" in the suburbs did not meet the meteorological "first snow standard". The monitoring of the observatory in the southern suburbs of Beijing shows that there has been no effective precipitation in Beijing for 77 consecutive days from 20 17123 to 20 1817.

Recently, snowfall occurred in more than 20 provinces across the country. Why bypass Beijing? Experts say that cold air, sufficient water vapor and meteorological conditions are the three elements of snowfall, while Beijing has only "cold air".

According to the definition of the first snow day in Beijing, the first snow day that meets one of the following conditions is the "first snow day": more than 10 stations in 20 artificial stations in Beijing have observed snowfall; Snowfall was observed at five stations in the urban area (Chaoyang, Haidian, Fengtai, Shijingshan and Meteorological Observatory). Snowfall has been observed in 3 or more of the 5 stations in the urban area, and the snowfall at least 1 station is 0. 1 mm or more.

Shi Hongbo, climate forecasting office of Beijing Climate Center, said that snowfall needs three conditions: precipitation meteorological system, sufficient water vapor and cold air.

20 17, 17 Since February, there is only one condition for "cold air" in Beijing, Tianjin and Hebei, that is, the north wind is strong, but the water vapor condition is poor, which belongs to "dry and cold type". On some days, the air humidity does not exceed 30%, and the meteorological conditions for snowfall are insufficient.

Since the 2nd, there has been a wide range of rain and snow in central and eastern China, but the snowfall has avoided Beijing and Tianjin.

Zhang Tao, chief forecaster of the Central Meteorological Observatory, said that the heavy snow in the central and eastern regions was caused by the strong warm and humid airflow from the Bay of Bengal. Warm and humid air flows into China from the southwest, and meets with weak cold air from north to south in the eastern part of northwest China, southern North China, Huanghuai, Jianghuai and Jianghan, and continues to be wet and cold, which promotes the formation of large-scale rain and snow weather.

Experts pointed out that the intersection is in the south, and the warm and humid airflow has not reached the north, so it has not snowed in the north.