Can't sleep!The night is getting hotter!"All -weather" high temperature is more?

Hot summer

If it is just hot during the day

Reflute at night

That's acceptable

But if it is hot during the day

Continue the "steamer" mode at night

No chance to breathe at all

That's it so hot that it is thorough

this summer

This is exactly the case experienced in many places in the south

Not only during the day hot

The lowest temperature at night also exceeds 35 ℃

August 20th

Chongqing Shapingba

At 22:25, the temperature is still "high" 39 ℃

In this long -lasting high temperature process

A clear feature is

many places

Not only hot during the day, but also hot at night

"Why is there a heat wave at night without the sun?"

"Where does this heat wave come from?"

"Is it more difficult at night at night?"

There will be more and more heat waves at night!

my country generally refers to the high temperature of the daily maximum temperature or more than 35 ° C. The high temperature weather process for several consecutive days is called high temperature heat waves.

At night, as the name implies, the high temperature heat waves at night, that is, the night temperature continues to be high. Although it appears at night, "force value" and "destruction value" cannot be ignored. At night, the heat wave is good at confusing people with darkness at night, making people take it lightly, and then releases a lot of calories.

Shapingba Station was 9:00 on August 16th to 9:00 on the 17th, and only an hour temperature was lower than 35 ° C within 24 hours

A cooperative team from the Institute of Atmospheric Physics of the Chinese Academy of Sciences, the Chinese Institute of Meteorological Sciences, and the University of Edinburgh will subdivide high temperature events into daytime and high -temperature (hot during the day, not hot at night), high temperature at night (not hot during the day, hot at night, heat at night ) And during the day-night composite (continuous heat during the day and night), and the temperature of the day and night during the summer is 10%of the top 10%of the day, it is called "composite extreme high temperature event".

The team believes that under the impact of climate change caused by human activities, the composite extreme high -temperature events will increase significantly. By the end of this century, the population of the northern hemisphere was exposed to such incidents 4 to 8 times higher than the 2010s.

This study pointed out that if we do not carry out any emission reduction measures, such incidents will increase almost monotonous with global warming. By the end of this century, three -quarter summer periods may become "all -weather" that continues to heat during the day and night. Extremely high temperature.

There is no sun at night, where does the heat wave come from?

The physical mechanism that causes high temperature during the day and night is related to the interaction of land gas and meteorological conditions. Usually we believe that the temperature after the sunset will naturally decrease, but the actual energy accumulated during the day is slowly released at night. The heat accumulated in the atmospheric boundary during the day can be preserved until night, so the high temperature can last until night.

The time sequence and trend picture source of the number of night heat waves in China from 1980-2017: SHI, Z. Et Al., 2021

At night, due to factors such as hot island effects, the high temperature in the city will last longer, and the temperature decreases slowly. If it is under the wet meteorological conditions (commonly known as "sauna"), there is a cloud layer at night, and it is covered with a warm hood like a greenhouse. The strong downward long waved radiation can also cause higher temperature at night.

The main reason for the formation of night heat waves is two points:

First, urbanization has led to a decrease in evaporation and weakening wind, which has strengthened the hot island effect.

City hot island effect diagram picture Source: GosmartBricks

The second is that in addition to reducing evaporation and wind, the dark roads of the city have increased the heat storage during the day and enhanced the long -wave calorie release at night.

In general, the degree of urbanization of different development has different contributions to night heat waves. The higher the development level of the city, the more the lower the surface is paved, the worse the water seepage capacity, the larger the corresponding water surface area, the decrease in the evaporation of the surface, but the heat absorption increases, and the city will continue to heat the city.

What are the hazards of the heat wave at night?

The influence of the heat wave on human society should not be underestimated. The most important thing is that the increase in temperature at night will reduce people's cooling ability and prevent the human body from recovering from high temperature exposure during the day, thereby increasing the risk of heat stroke, cardiovascular disease and death.

An international cooperation study published in "Liuye Knife -Star Health" in August this year pointed out that it is expected that at the end of this century, the night temperature caused by climate change will increase the global mortality rate by 60%.这支由中、韩、日、德、美科学家组成的研究团队称，到2090年，在东亚的28个城市，“热夜”事件的平均强度将翻一番，温度将从20.4℃增加至39.7 ℃. Excessive temperature destroys the normal sleep mode, thereby increasing the burden on the disease.

The hot environment at night may interfere with normal sleep. Insufficient sleep will cause the immune system and mental health, and increase the risk of cardiovascular disease, chronic diseases, inflammation, etc.

The picture shows a 101 -year -old man in 1995 in the Chicago heat wave in the United States. This high -temperature heat wave event caused about 600 people to die about heat stroke

In 2003, the fatal heat wave swept Europe, causing about 15,000 people in France to die

In addition, high temperature at night will increase electricity load. In the past, the temperature decreased at night in summer, and the use of air conditioners and other uses decreased. However, in the "hot night", people need to turn on the air conditioner all night to cool down, and the energy consumption is added invisibly.

In addition, for European countries without air conditioning habits, the "hot night" has led to people in the deep water. The high -temperature heat wave warning system in many countries only considers the daytime situation and ignores the night. This is also the "cunning" of the night hot waves. What can we do for night heat waves?

The impact of high temperature at night on the human body is largely reflected in sleep. You can use the fan or air conditioner in advance to reduce the room temperature and use the breathable bamboo bedding. However, in the case of heat day and night, we must pay more attention to avoid "air conditioning diseases" such as headaches caused by hypoxia causing hypoxia all day long.

The diet can be lighter. Avoid eating big fish and big meat and high oil before going to bed, because the process of digesting food can also cause an increase in body temperature.

In the long run, how to ease the heat wave at night? In urban planning and construction, the selection of roads and building materials, the choice of house color, the interval between buildings and ventilations, etc. should be considered; increasing the attention of the heat wave at night, so that the public has some understanding of this "weather assassin" Prevent.

Night comes to the city to shoot: Zhang Aiyue

To fundamentally reduce the occurrence of night heat waves, it is necessary to jointly take emission reduction measures around the world to slow down climate warming.

He is committed to studying the "Night High temperature" incident, Professor Xi Haidong, a professor of Fudan University:

""

When evaluating the burden of disease caused by the non -best temperature, the decision makers should consider the additional effects of daytime temperature changes on health. Making a more comprehensive health risk assessment on future climate change can help decision makers better allocate resources and determine priority matters.

"

Produced by China Meteorological News Agency

Reference materials: China Meteorological News, Institute of Atmospheric Physics, Chinese Academy of Sciences

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