Small heatstroke is not considered hot, big heatstroke occurs on a hot day. "Three hot days, appearing between small heatstroke and heat stroke, are a period of hot, humid, and stuffy summer days. Famous cultural scholar Cui Daiyuan said that at this time, the customs in old Beijing were more daily, and people were busy changing window screens and laying cold mats to resist the hot weather. In addition, they will also go swimming in Shichahai, go boating in Beihai, eat watermelon, drink jelly and so on. "In the summer, Beijingers pay attention to eating water cooled noodles. The best way to cross the water surface is sesame paste noodles. The main seasoning is sesame paste boiled with water. In the small ingredients, onion soy sauce is essential. There is also a special seasoning, mustard sauce." Cui Daiyuan said. In his opinion, summer is full of vitality, and everyone should do their best to live their best. ▲ Data map: A mouthwatering milk watermelon. The formation of the 24 solar terms during the three gengs of the summer solstice recorded by Li Jinghai went through a relatively long process. There is an idiom called "immediate effect". Simply put, the ancients determined the solar term based on the shadows on the ground. The ancients discovered that the shadow of a tree was the clearest at noon during the day, and when it got hot, one day the shadow was the shortest, leading to the summer solstice. When it was cold, one day the shadow was the longest, leading to the winter solstice. "Cui Daiyuan explained that the ancients also discovered that there was one day in spring and autumn that was as long as the day and night, so they used the shadows of these two days to determine the spring and autumn equinoxes. This is' two to two '. For the vernal equinox, Cui Daiyuan wrote in "Twenty four solar terms? Biting Spring" that "standing" means the beginning, starting from the beginning, everything is renewed, and a brand new spring begins like this. However, he also stated that the 24 solar terms were born in the culture of guiding agricultural production in the middle and lower reaches of the Yellow River, so they are not universally applicable. For example, a friend who has lived in Hainan for a long time finds it difficult to understand what "heavy snow" means. According to the calculation method of the ancients, Toufu is the third "Geng" day after the summer solstice, with a difference of ten days between Toufu and Er Fu. Cui Daiyuan said that there is generally a gap of fifteen days between small heatstroke and large heatstroke, and the annual small heatstroke corresponds to the head depression, while the large heatstroke corresponds to the middle depression. A small heat stroke means entering midsummer, followed by a large heat stroke in the blink of an eye. With the arrival of a heatwave, the weather began to become stuffy, and only heavy thunderstorms could slightly reduce the heat and humidity. There are also years when the heat is not very hot, but that may mean "the heat is not transparent, the heat is after autumn". Summer customs: changing window screens and eating watermelons. The summer solar terms have their own charm. The sixth day of the sixth lunar month is often after a small summer, and it is said that in ancient times, this day was called "Washing and Drying Festival". People should take a quick bath and wash their clothes and bedding to dry. ▲ "The Good Taste of the 24 Solar Terms? Biting Spring". Published by Tiantian Publishing House. The 24 solar terms on the tip of the tongue, each with its unique flavor. In "The Taste of the 24 Solar Terms? Biting Spring", Cui Daiyuan wrote about the changes in the four seasons, the memories of customs, the knowledge behind the scenery, as well as the beauty of traditional Chinese solar terms and the richness of culture. The same goes for summer. For Cui Daiyuan, when summer comes, he remembers the customs of old Beijing, such as changing window screens, laying summer mats, smoking mosquito repellent incense, swimming in Shichahai, boating in Beihai, eating watermelons and drinking