Long summer is the seventh of the 24 solar terms and the first solar term in summer, which indicates the official start of summer. The bucket refers to the southeast, and the dimension is long in summer. Everything has grown to this day, hence the name Long Summer.

When the sun moves to the longitude of the Yellow River at 90 degrees, it is the intersection of the summer solstice, usually on June 2 1~22 of the Gregorian calendar. On the day of summer solstice, the position where the sun shines directly on the ground reaches the northernmost part of the year, almost directly on the tropic of cancer. At this time, the daylight hours in all parts of the northern hemisphere reach the longest in the whole year.

2. Different characteristics

The summer solstice is the northernmost day of the sun in a year and the limit of the sun's northward movement. The solstice in summer is the turning point of the sun. After this day, it went back, and the direct sunlight point began to move south from the Tropic of Cancer (23 26' north latitude), and the days in the northern hemisphere became shorter day by day. After the summer solstice, the Tropic of Cancer and its northern region, the midday sun altitude angle also began to decrease.

Chang Xia said that saying goodbye to spring is the beginning of summer. According to the standard of climatology, summer begins when the average temperature of that day rises above 22℃. Before and after the "Long Summer", only the area south of Fuzhou-Nanling Line really entered the summer in China, while some areas in the northeast and northwest just entered the spring at this time, and the average temperature in most parts of the country was around 18-20℃.

3. The temperature is different

In the long summer, the temperature in the north and south of China is very different, and fluctuates frequently in the same area. The temperature in the rest of South China is around 20℃. The low-altitude valley felt hot in summer as early as mid-April, and the temperature in long summer was above 24℃.

Although the sunshine duration from summer solstice is the longest, it is not the hottest time of the year. For the Yellow River in China and most of its northern areas, the highest monthly average temperature is July, followed by August and then June.

Baidu encyclopedia-summer solstice

Baidu Encyclopedia-Long Summer