How to determine the onset time of the ambush?, The dog days officially begin today with high temperatures | summer | summer
The process of entering the summer and hot weather in meteorology is not a set of standards. The Fu Tian is determined according to the ancient Chinese "Gan Zhi Ji Ri Fa"
On July 11, this year's dog days officially opened. Did you know that not only the number of days in the summer of each year is not fixed, but also the date when the summer begins.
On July 11th, this year's dog days officially began. Do you know? The number of days during the summer solstice each year is not fixed, and the start date of the summer solstice is also different.
As the folk proverb goes, "On the summer solstice, the number of gengs counts and the head falls.". However, the folk process of entering the summer and hot weather is not the same as the meteorological process of entering summer and high temperature. Fu Tian was determined according to the ancient Chinese "Gan Zhi Ji Ri Fa". The third day of the Geng Festival after the summer solstice is the first fu, the fourth day is the middle fu, and the first day of the Geng Festival after the beginning of autumn is the last fu, collectively known as the three fu. According to the Gregorian calendar, it occurs from mid July to mid August, regardless of geographical location. In meteorological terms, summer refers to the continuous increase of daily average temperature above 22 degrees Celsius for 5 days as the beginning of summer. From a national perspective, regions that meet the conditions often gradually enter summer from south to north.
According to statistics from the China Meteorological Administration, the first regional high temperature weather process in China this year was 16 days earlier than usual. As the saying goes, "Heat is in the three summers.". It is often very hot during the dog days, because after entering the dog season, the surface absorbs more heat and releases less heat each day. The heat in the surface layer continues to accumulate, making it hotter day by day. Entering the hottest period, the accumulated heat on the ground area reaches its peak. As the temperature rises, the atmospheric circulation also undergoes changes, mainly caused by the oscillation of the subtropical high pressure from south to north. Around June 18th this year, the southern region entered a rainy season, and the subtropical high pressure remained relatively stable, causing frequent heavy rainfall in southern China. The northern region is affected by high-altitude cold eddies, and sporadic process thunderstorms occur frequently.
The northern and southern regions are both very hot during the summer solstice, but the most obvious difference is that the heat in the north is dry and hot, with more process thunderstorms; The south is stuffy and hot, accompanied by continuous rainy plum rain weather.
Taking the high temperature weather in the North China and Huanghuai regions since June this year as an example, it is characterized by extremely high temperatures, strong solar radiation, and low air humidity, making it a typical dry hot type of high temperature weather. This is related to the continental metamorphic high pressure controlled by the continental warm ridge. Due to its location in the hinterland of Asia, the vast mountains surrounding the inland and northwestern regions block the warm and humid air currents in the Indian Ocean and Atlantic Ocean. When controlled by the continental warm high pressure, it is easy to form extremely strong sunlight. In addition, due to the low surface water content, it cannot achieve the effect of water evaporation, heat consumption, and cooling, resulting in a rapid rise in temperature and the formation of high-temperature weather, which continues to be hot. The reflection in meteorological elements is that there is a significant difference between the daily highest and lowest temperatures, usually above 10 degrees Celsius, and humidity is around 30%.
During the same period, the occurrence of high temperature weather in the southern region is generally closely related to subtropical high pressure. When controlled by the subtropical high pressure system in the western Pacific, it is difficult for cold air from high latitudes to reach vast areas in the south. At the same time, the sinking airflow inside the subtropical high pressure suppresses the development of clouds and rain, accompanied by a sinking warming effect. Coupled with high humidity, people feel stuffy and hot, just like in a steamer. This type of weather is called stuffy and hot high temperature. Such weather often occurs along the coast of China, in the middle and lower reaches of the Yangtze River, and in southern China. The reflection of meteorological factors is that the difference between daily maximum and minimum temperatures is relatively small, generally within 5 degrees Celsius and humidity above 60%.
