The cold wave is coming again! Scientists say the world is warming, why are winters still so cold?
The New Year’s Eve cold wave in 2020 has just passed, and the cold wave in 2021 has already been shipped. At present, the Central Meteorological Observatory has issued a cold wave blue warning: In the next three days, due to the influence of strong cold air, the temperature in central and eastern parts of my country will generally drop by 6-8°C. Among them, the temperature drop in western North China, Huanghuai, Jianghuai, and Jiangnan regions can be Reaching above 10 degrees Celsius, accompanied by northerly winds of magnitude 4-6 and gusts of magnitude 7-9. The formation of a cold wave
Many people may think that a cold wave is cold air, but this is not the case. It only occurs when the temperature drops by 8 degrees Celsius within 24 hours, or by 10 degrees Celsius in 48 hours, or by 12 degrees Celsius in 72 hours. And only when the lowest temperature throughout the day is below 4 degrees Celsius can it be called a cold wave.
The cold wave warning level 1*** has three levels, of which blue is the weakest, followed by yellow and orange is the strongest. The New Year's Eve cold wave in the past few days was an orange-level cold wave, but this time it is a blue-level cold wave. Even so, areas affected by the cold wave will also experience a wave of "quick freezing cooling", so they must be prepared for disaster prevention and relief.
Every time a cold wave is broadcast in the weather forecast, it is always said to be "affected by cold air from Siberia", but in fact Siberia "does not produce cold air, they are just transporters of cold air."
The cold waves that affect our country mainly originate from three places, namely the ocean to the west of Novaya Zemlya, the ocean to the east of Novaya Zemlya, and the ocean to the south of Iceland. It is located near the Arctic Circle and receives less sunlight in winter, so the temperature is very low. In places with low temperatures, the air pressure is high.
The cold air from these three places will reach the Siberian region, so Siberia will also become a key development area for cold waves. With the cooperation of blocking high pressure and the polar vortex, the cold air will be here When the accumulation continues to become stronger, part of the cold air will "overflow" like water and reach the southern region. This is the cold wave that affects our country.
If the cold waves are distributed and shipped, that is to say, a small amount of cold air "overflows" each time, then the cold air will not cause a sharp drop in temperature when passing through; but if the cold air has been developing in Siberia and If cold air is sent to our country at once, the temperature will drop rapidly wherever the cold wave passes, causing serious losses to our country'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 currently facing the threat of warming, so why is this winter so cold?
According to statistics from the Central Meteorological Administration on strong cold air and cold waves in my country's history, our country has an average of 4.2 cold waves every year. Among them, strong cold air is mainly concentrated from December to February of the next year, while cold waves are mainly Focus on November.
However, in recent decades, the frequency of cold waves has decreased significantly, with a reduction rate of 0.4 times every 10 years. From this, it can be seen that the occurrence of cold waves is indeed affected by global warming. Influence.
Although the frequency of cold waves has decreased, it is not impossible. As long as the cold waves move south, severe cooling, ice, snow, strong winds, low temperatures and other weather conditions will still have an adverse impact on our lives.
Of course, part of the reason why it is exceptionally cold this year is related to the occurrence of La Nina. La Niña, like El Niño, is an abnormal sea temperature in the central and eastern Pacific Ocean. When the temperature in the western Pacific is higher than the temperature in the eastern Pacific, it will trigger a La Niña phenomenon; conversely, it will be an El Niño phenomenon.
El Niño occurs on average once every 7 years, and each time it occurs, it will cause the temperature to rise in some areas; La Niña generally occurs after El Niño, and La Niña will have a cooling effect on global temperatures.
It is understood that a weak to moderate La Niña event will form this winter. However, because the heat retained by greenhouse gases in the atmosphere offsets part of the cooling brought by La Niña, the degree of cooling this year is not obvious. . Despite this, temperatures this winter are still a little colder than this time last year. Summary
In fact, climate is a comprehensive system, and small changes in many factors within the system will cause a "butterfly response" in the climate. It is understood that factors such as melting of Arctic sea ice, changes in Eurasian snow cover, and the La Niña phenomenon will all affect my country's winter climate. Therefore, global warming alone cannot directly determine my country's winter temperatures. In other words, although we are facing the threat of global warming, we still cannot prevent the formation of cold air this winter.