What day is the autumnal equinox of 202 1? What are the characteristics of the autumnal equinox solar terms?

What day is the autumnal equinox of 202 1?

The autumnal equinox of 202 1 falls on August 17 of the lunar calendar and on Thursday, September 23rd of the new calendar at 3:20:55.

The autumnal equinox is the sixteenth of the twenty-four solar terms and the fourth solar term in autumn. Struggle with yourself; Does the sun reach the ecliptic 180? ; Celebrated on September 22-24 of the Gregorian calendar every year.

The autumnal equinox was once the prototype of the traditional Mid-Autumn Festival. According to textual research, the Moon Festival was originally scheduled on the day of the autumnal equinox, but there is not always a full moon because of the different date of August in the lunar calendar every year. And the moon without the moon is a big spoil the fun. Therefore, the Mid-Autumn Festival later moved from the autumnal equinox to the Mid-Autumn Festival.

What are the characteristics of the autumnal equinox solar terms?

First, the temperature drops.

At the autumnal equinox, the Yangtze River basin and its vast northern area have entered autumn, and the daily average temperature has dropped below 22℃. The cold air mass in the north began to have some influence. The rainy season has just ended in most areas, and the weather is crisp in autumn.

After the autumnal equinox, the direct sunlight moved to the southern hemisphere, and the northern hemisphere got less and less solar radiation, while the ground lost more heat and the temperature dropped significantly.

Second, the length of day and night is equal.

On the autumnal equinox, did the direct sunlight reach the longitude 180? (autumnal equinox), almost straight to the equator of the earth, and the length of day and night is equal all over the world (regardless of the refraction of the sun's light by the atmosphere and the shadow in the morning).

After the autumnal equinox, the direct point of the sun continued to move from the equator to the southern hemisphere, and the days in the northern hemisphere began to shorten and the nights became longer, that is, the days in a day began to be shorter than the nights; The southern hemisphere is the opposite. Therefore, the autumnal equinox is also called the landing point. At the North Pole and South Pole, on the day of the autumn equinox, the sun is on the horizon all day.