The Climate Center analyzes why warm winters are so cold.

The Climate Center analyzes "Why is it so cold in warm winter" as follows:

There is a huge temperature difference between the equator and the polar regions, which makes a strong westerly wind form around the polar regions. This westerly wind is called westerly jet. Westerly jet is like a fence, which restricts the cold air in the polar regions. The mighty westerly jet confined the stable polar vortex to the North Pole. In the context of global warming, the warming rate of the Arctic is 2-3 times that of the whole world. As the temperature in the Arctic rises, the temperature difference between the Arctic and the middle and low latitudes weakens, making it difficult to maintain a strong westerly jet, and the cold air in the polar vortex becomes "restless", which makes it easier to split south.

Some countries and regions around the Pacific Rim and the equator are the first to be affected by El Ni? o in the world. At the same time, El Ni? o will also lead to increased rainfall in southern South America, southern United States, Horn of Africa and parts of Central Asia, and lead to severe drought in Australia, Indonesia and parts of South Asia.

For our country, since 1990s, from the summer of El Ni? o development year to the summer of the following year, the areas with more precipitation have extended from the north and south of the Yangtze River to the Huaihe River Basin, with the most obvious precipitation anomaly in winter.

The influence of El Nino on China in winter and summer is stronger than that in summer and autumn. For example, during the flood season of 1998, violent plum blossoms appeared in China, and continuous heavy rains in the Yangtze River basin triggered basin floods. In winter when El Nino occurs, the precipitation in Huaihe River, Yangtze River and Pearl River basins is abnormally high, and the temperature in Northeast China is abnormally high, that is, it is rainy in the south and warm in the north.

Extreme weather in history

On February 7, 202014-/kloc-0, a nationwide cold wave process affected China, and the temperature dropped by 8 ~ 12℃ in most areas and exceeded 18℃ locally. Snowfall (rain) occurred in the northeast, eastern North China, Huanghuai and other places, and the maximum snow depth of 7 stations in Jilin Province exceeded 40 cm; Heavy rain or torrential rain occurred in Guangdong, Guangxi and other places, and disastrous weather such as hail, strong wind, lightning and road icing occurred in many provinces.

On 2016 65438+1October 20-25, strong cold air affected most parts of China from north to south; The temperature drop in China is over 6℃, covering an area of 7.86 million square kilometers, with the temperature drop in 529 counties and cities exceeding 12℃ and 18℃ in 6 counties and cities. The continuous cooling range of 23 stations exceeded the historical extreme value, and the daily minimum temperature of 67 counties and cities exceeded the historical extreme value; On the 25th, the first snowfall occurred in Guangzhou since the founding of the People's Republic of China.

Refer to the above contents: China Meteorological News-A moderate-intensity El Ni? o event has formed a composite meteorological disaster risk or increased.