Weather forecast in Taizhou coastal area

The New Year's cold wave in 2020 has just left, and the cold wave of 202 1 has already arrived. At present, the Central Meteorological Observatory has issued a blue warning of cold wave: in the next three days, due to the influence of strong cold air, the temperature in central and eastern China will generally drop by 6-8℃, and the temperature drop in western North China, Huanghuai, Jianghuai and Jiangnan will reach 10℃, accompanied by northerly winds of 4-6 and gusts of 7-9.

The formation of the cold wave Many people may think that the cold wave is cold air, but it is not. Only when the temperature drops by 8 degrees Celsius within 24 hours, or by 10 degrees Celsius within 48 hours, or by 12 degrees Celsius within 72 hours, can it be called a cold wave.

There are three levels of cold wave early warning, of which the blue level is the weakest, followed by yellow and orange is the strongest. A few days ago, the New Year's cold wave was orange, and this time it was blue. Even so, the areas affected by the cold wave will experience a wave of "quick freezing and cooling", so we must be prepared for disaster prevention and relief.

Every time the weather forecast broadcasts a cold wave, it always says "affected by Siberian cold air", but in fact Siberia "does not produce cold air, they are just porters of cold air"

There are three main sources of cold wave affecting China, namely, the west of Xindi Island, the east of Xindi Island and the southeast of Iceland. It is located near the Arctic Circle. There is little sunshine in winter, so the temperature is very low. Where the temperature is low, the air pressure will be higher.

The cold air in these three places will reach Siberia, so Siberia will also become the key development area of the cold wave. With the cooperation of blocking high pressure and polar vortex, cold air will accumulate here. When the accumulation becomes stronger, some cold air will "overflow" to the south like water, which is the cold wave that affects our country.

If the cold wave distributes the goods, that is to say, a small amount of cold air "overflows" every time, the temperature will not drop sharply when the cold air passes through the border; However, if the cold air has been developing in Siberia and sent to China at one time, the temperature in the place where the cold wave passes will drop rapidly, which will bring serious losses to China's agriculture, animal husbandry and other industries.

Why is it so cold this year? In the past few months, scientists have predicted that this year will be a cold winter. However, we know that the world is facing the threat of global warming, so why is it so cold this winter?

According to central weather bureau's statistics of strong cold air and cold waves in China's history, it is found that there are 4.2 cold waves in China every year on average, in which strong cold air mainly concentrates in 65438+February and cold waves mainly concentrate in165438+1October.

However, in recent decades, the frequency of cold wave has obviously decreased, decreasing by 0.4 times every 10 year, which shows that the occurrence of cold wave is really affected by global warming.

Although the number of cold waves has decreased, it is not impossible. As long as the cold wave goes south, strong cooling, snow and ice, strong wind and low temperature will still have adverse effects on our lives.

Of course, the reason why this year is particularly cold is related to the occurrence of La Nina to some extent. La Nina, like El Ni? o, is an abnormal seawater temperature in the central and eastern Pacific Ocean. Among them, when the temperature in the western Pacific is higher than that in the eastern Pacific, La Nina phenomenon will be triggered. On the contrary, it is the El Ni? o phenomenon.

El Nino occurs once every seven years on average, and each occurrence will lead to an increase in temperature in some areas; La Nina usually occurs after El Nino, which will cool the global temperature.

It is understood that there will be a weak to moderate intensity La Nina event this winter, but the cooling rate this year is not obvious, because the heat of greenhouse gases in the atmosphere offsets part of the cooling caused by La Nina. Nevertheless, the temperature this winter is still colder than the same period last year.

To sum up, climate is a comprehensive system, and small changes in many factors in the system will cause the "butterfly response" of climate. It is understood that the melting of Arctic sea ice, the change of snow cover in Europe and Asia, La Nina phenomenon and other factors will affect the winter climate in China, so global warming alone cannot directly determine the winter temperature in China. In other words, although we are facing the threat of global warming, we still can't stop the formation of cold air this winter.