Why did it suddenly get cold?
In winter, the land temperature is lower than the ocean temperature, which forms a strong cold high pressure in the mainland, and the air flow diverges in all directions from the high pressure center. The air mass moving to low latitudes belongs to cold air mass in nature, and when it meets warm air mass, it forms a cold front. When the cold front crosses the border, it becomes rainy (snowy), windy and cool. After crossing the border, the temperature and humidity dropped sharply and the air pressure rose. In winter, the cold air mass moves southward rapidly (in the northern hemisphere, but in the southern hemisphere), which often leads to disastrous gale, cooling weather and even cold wave.
In this way, the snowfall area in winter (the same as the rainfall area in summer) is distributed near the front, that is, the intersection of cold and warm air masses. This position is not fixed, but is determined by the strength of the two air masses. The cold air mass is weak, the front and precipitation areas have high latitudes, the cold air mass is strong, and the front and precipitation areas have low latitudes.
The land cold high that affects China in winter is the Asian high centered on Mongolia and Siberia (also known as the Mongolian Siberian high), which has a very large sphere of influence and has a great impact on the weather in China, especially in the northern region.
Since the beginning of winter, especially since 2008, the high pressure in Asia has been very active, and cold air masses have been formed continuously, which has affected China and caused large-scale gale and cooling weather. For China monsoon climate zone with great seasonal and interannual changes, this kind of weather is normal, but due to the active heating mass in the south this year, a large number of warm and humid air currents from the Pacific Ocean and the Indian Ocean frequently visit the south. When the strong cold air mass from Mongolia and Siberia quickly moves south to the south, it mixes with warm and humid air.
As the saying goes, it takes two hands to make a sound. If there is only a strong cold air mass without a large amount of water vapor provided by a warm wet air mass, there will only be strong winds and cool weather in the south; If there is only a large amount of water vapor provided by warm and humid air masses, there will be no disastrous weather at all without the arrival of cold air masses. When both are ready, disaster comes.
In this disastrous weather, the northern part of China was mainly affected by strong winds and cooling weather. The cold air mass goes north and south, and there is no front here. There was no heavy snowfall, but the north was later incorporated into the powerful Asian high pressure circle, and the degree of dry and cold weather was rare in recent years.
The climate in southern China is dominated by subtropical monsoon, and the temperature in winter is generally above 0 degrees. Agricultural production has overwintering crops, residents do not need heating facilities, ordinary families do not have enough warm clothes, and drivers are generally not worried about diesel freezing. All these have caused great destructive power of this disastrous weather.
A large number of overwintering crops were frozen to death in the gale and cooling weather brought by the strong southern air mass, and agricultural production was greatly reduced or never harvested, including winter wheat, overwintering rape and green manure crops. A large number of livestock froze to death.
In industrial production and transportation, all kinds of vehicles fueled by diesel oil can't run normally at low temperature because of the freezing of diesel oil, which further affects the economic benefits of related industries. Heavy snow blocked traffic and affected a large area. Rainwater presses power lines in winter, which affects power and communication.
The life of residents is seriously affected, and the low temperature freezing injury means that a large number of people are frostbitten or even frozen to death. Heavy snow collapsed the roof, causing casualties and property losses. Heavy snow blocks traffic, affects people's travel and affects the supply of daily necessities. In addition, it will have an immeasurable impact on household heating, gas supply and power supply.
This disaster warns us that we should plan ahead and be prepared for danger in times of peace, otherwise we can only learn from the bitter experience and regret it too late. Combined with the lessons brought by this disaster, we must carry out relevant national education, start with dolls in the future, engage in some relevant drills at the right time, and always be vigilant.