In the past few days, the daily maximum temperature of national meteorological observatories in many places in the north has exceeded the historical extreme value, constantly refreshing the historical record. The southern region is a completely different scene. Chongqing, Wuhan, Nanchang and Changsha, which used to be hot in summer, were unusually "calm". From June 22 to 23, the daily maximum temperature of 21 national meteorological observatories in Beijing, Tianjin, Hebei, Shandong and other places has exceeded the historical extreme.
As of June 24th, the temperature of the observatory in the southern suburbs of Beijing has reached 40℃ for three consecutive days, which is the first time that the temperature of the observatory has exceeded 40℃ for three consecutive days since its own meteorological record.
In the early morning of July 6th, the Beijing Meteorological Observatory upgraded and released the high-temperature red warning signal: It is estimated that the highest temperature in most parts of the city will rise above 40℃ on the 6th.
01
Where does "heat" come from?
What is the reason for the high temperature intensity and long duration in the northern region this year? First, the northern region is controlled by a strong heating mass, and the influence time is long; Second, under the control of the high-pressure ridge situation, the weather is mainly sunny and hot, and there is no cloud cover, and the temperature rises faster; Third, after entering the summer solstice season, the daytime is the longest, and long-term sunshine also "adds a fire" to the formation and maintenance of high temperature; Finally, the low air humidity and dry weather in the northern region can be described as "adding fuel to the fire". The combined effect of the above factors makes the northern region frequently undergo high-temperature "baking" tests.
Image source: Xinhua News Agency
High temperature occurred in June, is this related to this year’s El Nino? According to the forecast of the National Climate Center, El Nino will be maintained in the equatorial Middle East and Pacific Ocean in the next three months. The continuous rise of sea surface temperature and the superposition of moderate or above intensity El Ni? o events may lead to more frequent, wider and stronger extreme weather.
Therefore, whether in the south or the north, the frequency of extreme high temperature weather is increasing. However, the factors affecting climate anomalies in China, especially extreme events such as high temperature and drought, are complex, and El Ni? o is only one of them, and its influencing mechanism is also uncertain.
02
"Hot" over the South?
In late June of last year, the average value of the highest temperature in North China, Huanghuai and other places was basically the same as that in the south, but judging from the maximum value of the highest temperature, the north in June was indeed hotter than the south.
There are obvious regional differences in high temperature concentration periods in various parts of China. From the climate point of view, after entering the summer, the temperature rise in China presents the characteristics of "north first and then south".
In North China, high temperature weather is more likely to occur from June to early July, that is, before the rainy season. It is more common to have high temperature for several days, mainly dry-hot high temperature, which is characterized by high temperature and low humidity. In late July, with the subtropical high jumping northward and the summer monsoon advancing northward, water vapor transport and atmospheric humidity will increase, and cloud cover will also increase, resulting in sultry weather, that is, humid and hot high temperature.
In short, the high temperature in the north is often concentrated in early summer, while the south enters the high temperature season in midsummer. Therefore, at present, China is in the pattern of "high temperature in the north and heavy rain in the south", and the subsequent rainfall in the south will weaken and the high temperature weather will increase.
03
Will it get hotter after falling?
Incubation is a general summary of temperature and humidity. China usually enters into hibernation around mid-July, and the subtropical high rises northward to control the northern region, resulting in the weather phenomenon of no rain, high temperature and high humidity.
Generally, it is represented by "sauna days" after sleeping, which is quite different from the sunny and hot, dry and hot weather. As far as people’s personal feelings are concerned, somatosensory temperature is not only related to temperature, but also affected by humidity. Because of the high humidity, the sweat discharged from the body can’t evaporate and the heat can’t dissipate. At this time, people’s somatosensory temperature is also higher, and they will feel sultry and prone to heatstroke.
In the future, the rain belt will gradually move northward, and the northern region will enter the rainy season, and the dry and hot weather will end and turn into sultry weather. At that time, the prevention of high temperature weather should be changed from high temperature and dry heat to high temperature and high humidity, and everyone should make a targeted response.
Produced by China Meteorological News Agency
Author: Li Qian
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