What is the longest and shortest day in a year?

The summer solstice (June 22nd) has the longest day, and the winter solstice (65438+February 22nd) has the shortest day.

The summer solstice falls on June 2 1 or 22 every year. On the day of summer solstice, the sun directly reaches the northernmost point of the year, almost directly to the Tropic of Cancer (23 26' 28 "44 north latitude), and the daytime in the northern hemisphere is the longest, and the farther north it is, the longer it is. It is the longest day in a year in the northern hemisphere, and it takes about fourteen hours from sunrise to sunset in the south of China. Although the summer solstice has the longest day and the highest sun angle, it is not the hottest time of the year. Because, close to the surface of the heat, at this time still continue to save, did not reach the maximum time. As the saying goes, "Hot days are in dog days", and the real hot weather is calculated by summer solstice and beginning of autumn. From mid-July to mid-August, the temperature is the highest in all parts of China, and the highest temperature in some areas can reach about 40 degrees Celsius.

Summer solstice was also called "Summer Festival" and "Summer solstice Festival" in ancient times. In the ancient summer solstice, people prayed for disaster and prosperity by offering sacrifices to God. "Zhou Li Chun Guan" contains: "With the arrival of summer, go to local things." Sacrificing to God in the summer solstice of the Zhou Dynasty means eliminating plague, famine and starvation. Historical Records records: "On the solstice of summer, people worship the land with music and dance." As an ancient festival, the summer solstice began in the Song Dynasty, and officials have a three-day holiday. In Liao Dynasty, this day was called "summer solstice", and women entered colorful fans to give each other a legacy (Liao history). In the Qing dynasty, it was also called "summer solstice is a day's transition, and the sun, the next day and the last day were called" three hours ",so people lived cautiously. Calculation of summer solstice date [y * d+c]-Interpretation of L formula: Y= two digits after the number of years, D=0.2422, L= leap year, 2 1 century C=2 1.37, and 20th century =22.20.

For example, the date of summer solstice in 2088 = [88× .0.2422+21.37]-[88/4] = 42-22 = 20, and the date of summer solstice is June 20th.

65438+February 22nd is the "winter solstice" among the 24 solar terms. When the sun meridian reaches 270 degrees, the winter solstice solar terms begin. In winter solstice, the sun shines directly on the tropic of Capricorn, with the shortest day and the longest night in the northern hemisphere, and the cold days begin from winter solstice.

The winter solstice is a very important solar term, and it is also a traditional festival in China's lunar calendar. Up to now, there are still many places where the winter solstice festival is held. The winter solstice is commonly known as "Winter Festival", "Dragon Solstice Festival" and "Asian New Year Festival". As early as 2500 years ago, during the Spring and Autumn Period, China had determined the winter solstice by observing the sun through the soil return, which was the earliest of the 24 solar terms. There is no 10 hour from sunrise to sunset in most parts of southern China. From winter to the future, as the earth orbits the sun, the direct sunlight belt gradually moves northward, making the days in the northern hemisphere gradually longer and the nights gradually shorter. On the solstice in winter, although the height of the sun is the lowest and the sunshine time is the shortest, the ground absorbs more heat than it loses. After the winter solstice, it begins to count to nine, and every nine days is a "nine". Before and after the "March 9th", the heat accumulated on the ground was the least, and the weather was the coldest. There is a folk proverb in China, "It's cold in three or nine days, but hot in three days".