There is only a cold wave from short sleeves to sweaters. During the National Day holiday this year, a strong cold air will bring large-scale strong cooling to the central and eastern parts of China from north to south. The cooling range in some areas such as Inner Mongolia, Heilongjiang, Jilin, Henan, Hubei and Anhui can reach above 18℃. The Central Meteorological Observatory issued the earliest cold wave warning in history at 10: 00 on October 2. Why did the cold wave come so early this year? What impact will the cold wave bring? How to prevent cold wave hazards?
Not all cold air is called cold wave.
The relationship between cold air and cold wave is often confused. Are cold air and cold wave the same thing? Min Yuqiu, a meteorologist of China Weather Network, said that cold wave is a kind of cold air, not all cold air is cold wave, but it is the "king" of cold air.
According to the degree of strength, cold air in China is divided into four grades: weak cold air, strong cold air, strong cold air and cold wave.
In the meteorological sense, the cold wave has a strict "threshold". Yang Shunan, deputy chief forecaster of the Central Meteorological Observatory, said that the cold wave weather process is a large-scale strong cold air activity process. According to the national standard of cold air, the daily minimum temperature in a certain place will be reduced within 24 hours ≥ 8℃, or cooling range within 48 hours ≥ Temperature drop at 10℃ or within 72 hours ≥ 12℃, and make the local daily minimum temperature ≤ The cold air activity at 4℃ is a cold wave. However, due to the geographical environment and climatic conditions, the cold wave standard will be different.
Why did you issue an early warning if you did not meet the cold wave standard?
Why did the cold air not reach the cold wave standard and also issued an early warning? Zhang Tao, chief forecaster of the Central Meteorological Observatory, explained that before and after the National Day this year, the temperature in the north and south of China increased significantly, and the temperature in many places reached new highs. This cold air force is very strong, which will cause severe cooling in most parts of central and eastern China. It coincides with the National Day holiday, and severe cooling may have an adverse impact on traffic, production and life. From the perspective of service, forecasters can issue cold wave warnings as appropriate, which has happened in the past.
The cold wave is the most frequent when it is not the coldest.
The cold wave began in late September at the earliest, and can last until May of the following year at the latest. As the king of cold air, we often think that the coldest time is the most frequent cold wave. This is not the case.
China Weather Network statistically analyzed the cold wave warning issued by the Central Meteorological Observatory in recent 11 years, and found that the cold wave process was the most in November, followed by December and March, and the coldest January and February were less.
Why is the cold wave in the middle of winter less than in the spring and autumn? Yang Shunan explained that spring and autumn belong to the seasonal transition period, the summer monsoon and winter monsoon switch, and the weather system and cold air activities are frequent, resulting in severe temperature fluctuations. Especially in autumn, the basic temperature in the early stage is relatively high, and the temperature often rises obviously before the start of a cold air. After the influence of cold air, the cooling range is very large, which is easy to form a "cliff-like" cooling, and it is relatively easy to reach the cold wave standard. In the middle of winter, the basic temperature is already low, and the cooling range is often limited when cold air strikes, so it is relatively rare to reach the cold wave standard.
It can reach South China when the cold wave is strong.
The cold wave that affects China is generally "born" near Xindi Island and Iceland. About 95% of the cold wave accumulates and strengthens in western Siberia, just like passing through a "gas station" and then affecting China in three ways, generally affecting the middle and lower reaches of the Yangtze River and the south of the Yangtze River, and some even reaching South China.
Yang Shunan introduced that most areas in China can be affected by cold wave weather. Except for the Qinghai-Tibet Plateau and Yunnan-Guizhou Plateau, there are obvious cold wave weather in other areas, especially in the northwest, northeast, north China and the middle and lower reaches of the Yangtze River. Feel the power of the cold wave.
From January 21 to 25, 2016, the overlord cold wave swept through most of China, with the cumulative cooling range of 12 ~ 18℃ in many places, exceeding 18℃ in some places, and the temperature of 0℃ pushed south to the central part of South China, and snowfall occurred in Guangzhou, Nanning and Hong Kong. Affected by this cold wave process, the area where the temperature drop is above 6℃ covers 90.1% of the national territory, affecting 1.18 billion people.
"two plus three defenses" should be done to defend against the cold wave
Cold wave is a large-scale disastrous weather process, which will cause large-scale sharp cooling, strong wind and rain and snow weather, and have a great impact on agriculture, animal husbandry, transportation, electricity and human health. In order to prevent and mitigate meteorological disasters, before the cold wave strikes, the meteorological department will issue a cold wave warning to remind the public to take preventive measures.
According to the "Central Meteorological Observatory Meteorological Disaster Warning Release Measures", cold wave warning is divided into three levels: blue, yellow and orange, with orange as the highest level. However, according to local characteristics and climate characteristics, all provinces, autonomous regions and municipalities issue their own meteorological disaster warning signals, which generally include blue, yellow, orange and red warning signals.
Once receiving the cold wave warning issued by the meteorological department, the public should pay attention to taking corresponding defensive measures to achieve "two plus three defenses" and add clothes; Reinforcement; Disease prevention; Non-slip; Prevent gas poisoning.
China Weather Network reminds everyone that there is no trivial matter when the cold wave strikes, and there is no child’s play in keeping warm and preventing diseases; Don’t be careless when traveling, and health and safety rank first. According to China Weather Network,
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