Beijing News (Reporter Li Yukun) The feeling of going out today is "frozen stupid." According to live monitoring, the temperature in most areas of the Beijing Plain was around -18°C at 19:00.

Among them, the observatory is -17.9℃, which has exceeded the extreme minimum temperature (-16.7℃) in early January of the past 20 years.

  The temperature will continue to drop at night on the 6th, and the temperature in the plain area is expected to be around -20°C on the morning of the 7th.

At present, the temperature in Beijing continues to drop. The Beijing Meteorological Observatory predicts that the lowest temperature in Beijing may reach -19°C tonight.

There are northerly winds of magnitude 4 and 5 in the city, with gusts of around magnitude 8, and local levels of magnitude 9 and above.

  The Central Meteorological Observatory continued to issue blue cold wave warnings at 18:00 on January 6.

Affected by the cold wave, it is expected that from 20:00 on January 6 to 20:00 on January 8, eastern and southern Northeast China, eastern Northwest China, central and southern North China, Huanghuai, Jianghan, Jianghuai, Jiangnan, eastern Southwest, and most of southern China , Taiwan Island and other places will drop by 6 to 8°C. Among them, the temperature can reach 10°C in parts of southern Shandong, most of Jiangsu, Shanghai, most of Zhejiang, northeastern Jiangxi, and northwest Fujian.

After the temperature drops, the 0℃ line of the lowest temperature will be pressed south to southern Jiangnan to northern South China, and the -10℃ line will be pressed south to Qinling to eastern Jianghuai.

There will be northerly winds of magnitude 4 to 6 and gusts of magnitude 7 to 9 in the Yangtze River Basin and its north.

Question 1: What is the wind chill effect?

  In the daytime today, the wind was particularly strong, and I was trembling in the wind.

  Meteorological expert Zhang Mingying said that this was actually affected by the wind chill effect.

The wind chill effect refers to the warm and cold that people feel, which is actually the body temperature, which is mainly affected by several factors.

  "The first is the temperature. The temperature is cold. The second is the effect of wind speed. The body is at a constant temperature and generates heat by itself. If the wind is strong, it will take away a lot of heat from our body, so the temperature will feel lower than the actual temperature. The third is humidity. If the humidity in the air is particularly low, it will feel better. If the humidity in the air in winter is high, it will take away more heat. Compared to the north, the temperature in the south is actually not so low, but many people are born. Why is it because of frostbite? It's because of high humidity." Zhang Mingying explained that there is another point, that is, body temperature is also affected by solar radiation.

The temperature is very low, such as today, but in a sunny place, it feels better. If you go to a shady place, it immediately feels very cold.

Question 2: Is this winter cold?

  Since the beginning of winter, three waves of cold waves have affected our country. Is this winter cold?

  Zhang Mingying said that cold winter is normal.

However, in recent years, due to the effects of global warming, winters seem to be getting warmer and warmer, and it doesn't seem to be so cold in winter.

  In fact, judging from long-term climate data, Beijing’s winter was quite cold in the 1950s, 1960s, and even 1970s, even lower than the current temperature.

In February 1966, there was a minimum temperature of -27.4°C.

  "Due to the global warming, the temperature in winter has been higher than the average for a long period of time. It is called a warm winter. This winter was also warm in the early period, but recently, the temperature It is relatively low. Everyone feels cold, which is also called cold winter. In fact, cold, warm and warm in winter is a very normal phenomenon. It is impossible to continue a warm winter, nor is it possible to continue a cold winter. The alternation of cold and warm is also a law of atmospheric changes. It's normal," Zhang Mingying said.

Question 3: Can Beijing really splash water into ice during the day?

  During the day today, many people tried an entertainment item unique to the Northeast-splashing water into ice.

  "I watched a few videos today. At that time, the temperature was around -10 degrees Celsius. If they poured out, they would actually form some water vapor instead of ice crystals. At minus 20-30 degrees Celsius in the northeast, what formed in the air was Ice crystals, ice crystals will sink quickly." Zhang Mingying believes that Beijing has not yet reached the northeast level. Low temperatures of minus 20 or 30 degrees often occur in the northeast, and water vapor instantly condenses into small particles. But now Beijing is pouring a basin of water onto the ground. It will not freeze instantly.

  At about 20 o'clock, the reporter conducted an experiment outdoors with a watering can, and the fine water droplets were still liquid when they were in the air.

However, on the surface of a cold object, those small drops of water will instantly condense into ice.

  During this cold wave, Beijing was already very cold. Why didn't it snow?

  According to analysis by Wang Weiyue, meteorological analyst of China Weather Network, the appearance of snowfall requires the combination of condensation nuclei, water vapor conditions, dynamic conditions and low temperature in the air. During this cold wave, Beijing did not transport warm and humid air currents and the water vapor conditions were poor. Snowflakes will not "patronize".

Question 4: What is a cold wave?

  Zhang Mingying said that the obvious feature of cold wave weather is suddenness. If the temperature drops slowly, there will be no cold wave.

  Cold waves are generally sudden, accompanied by strong winds and violent cooling, and the cooling range must reach a certain standard.

The cold wave standard in my country’s national cold air classification standard is that after the cold air in a certain area passes through the border, the temperature drops by more than 8 ℃ within 24 hours, and the minimum temperature is below 4 ℃, or the temperature drops by more than 10 ℃ within 48 hours, and the minimum temperature Below 4℃, or within 72 hours, the temperature continuously drops by more than 12℃, and its minimum temperature is below 4℃.

  Cold waves are generally most likely to occur in the early winter. In the severe winter, the cold air may not reach the cold wave standard, because the temperature is already very low at this time, and it is more difficult to drop 8°C.

When it is extremely cold, it is basically called strong cold air activity.

Question 5: Where does the cold wave come from?

  Zhang Mingying said that under normal circumstances, the cold air in the northern hemisphere comes from the north.

"The coldest place is in the polar region. The solar radiation in that place is very weak. In winter, there is basically no heating from the sun. The surface is relatively cold, so cold air accumulates in the Arctic region."

  However, the atmosphere is moving, and cold air will not gather in the Arctic. With atmospheric fluctuations and atmospheric circulation, the cold air will move back and forth from north to south, and it will affect areas in the south of the latitude.

When it gathers to a certain degree and the intensity is particularly strong, cold wave weather will form.

  As for why it is called Siberian cold air and not polar cold air, this is because the cold air mass stays in Siberia for a period of time during the process of moving southward, and gradually strengthens its development, and finally moves southward, affecting some places with relatively low latitudes. Caused continuous low temperature.

Question 6: What are the characteristics of this cold wave?

  Before the arrival of this cold wave, the Meteorological Department issued a warning that three waves of cold air will hit one after another by the 10th.

  Zhang Mingying said that the intensity of the cold air is relatively strong this time, and the high altitude temperature is particularly low.

At an altitude of about 5 kilometers, the temperature reached -55°C; at an altitude of 1500 meters, the temperature also reached minus 20 degrees Celsius, so the entire cold air temperature was low.

In addition, it has a wide range, from 5000 meters to the ground, which is a very thick mass of cold air.

  In addition, this time the cold air moved slowly and lasted a long time.

Generally, cold air affects Beijing for about 3 consecutive days, and then gradually shrinks northward, moves eastward, and begins to separate.