The beginning of autumn is the solar term that begins in autumn. The beginning of autumn occurs on August 7 or 8 every year when the sun reaches 135 degrees of ecliptic longitude.
After the beginning of autumn, many areas of our country began to blow northerly winds, and southerly winds gradually decreased. The small north wind brought a little coolness to the people. Because the daytime sunshine is still very strong, the cool breeze at night blows to form a certain temperature difference between day and night, and the water vapor in the air condenses into crystal dew drops on the outdoor plants in the morning. "The Three Marquis Chilling Cicadas"
At this time, the cicadas, with plenty of food and a moderate temperature, chirp triumphantly on the branches of the trees blown by the breeze, as if to tell people that the hot summer has passed. The first wait is 5 days, and the beginning of autumn is 15 days, and it gradually becomes cooler. Cooler is a climatic trend, and according to the description of the beginning of autumn, this may be the case during the colder climate.
The beginning of the autumn solar term indicates that the hot summer is coming to an end and autumn is coming. When the beginning of autumn arrives, many parts of our country are still in the middle of a hot summer. After the beginning of autumn, although the heat is difficult to get rid of for a while, and there is still the aftermath of the "autumn tiger", the general trend of the weather is that the weather is gradually cooler. The temperature difference between morning and evening is gradually noticeable, often during the day is very hot, and the night is cooler. Of course, due to the different climates across the country, the actual start time of autumn is also inconsistent.
Referring to the reasons for the formation of autumn tigers, the Dictionary of Atmospheric Sciences mentions that the subtropical high once again controlled the Yangtze-Huai River basin, and the temperature rose, forming a sultry weather. It can be seen that the weather in the south also cools after the summer, but it is not as obvious as in the north. The Dictionary of Atmospheric Sciences further points out that autumn tigers generally occur after the turn of August and September, and last for about a week to half a month, or even longer.
There are many years, the beginning of autumn is hot, the summer is still hot, so there is a big summer and a small summer is not a summer, the beginning of the autumn is just the summer, this kind of summer and autumn heat situation appears, "autumn tiger" more people's attention, need more reminders to prevent heat stroke and cool down.
At present, there is no uniform, quantitative standard for autumn tiger weather. According to experts from the Beijing Meteorological Observatory, the maximum temperature of autumn tigers is generally above 33 °C and lasts for several days. This statement is also for reference only.