When is autumn?

In autumn, the most obvious change of natural landscape is in trees. Urban society began to clean up a lot of fallen leaves, and many tourists went into the mountains to see the maple red.

Autumn is a transitional season from summer to winter. The lunar calendar is from beginning of autumn to beginning of winter from July to September, the solar calendar is from 9: 00 to165438+1October, and the astronomical cycle is from the autumnal equinox to the winter solstice.

The main meteorological disasters in autumn are: autumn rain in West China, cold dew wind in the south, frost and chilling injury at low temperature. Generally speaking, in autumn, the solar altitude angle decreases and the temperature decreases; The autumn wind is cool, the summer heat is gone, the fruits are covered with branches, and the fields are golden.

Autumn, also known as autumn, is the third season of the year. The transition season from summer to winter is from September to 165438+ 10 in the northern hemisphere, from March to May in the southern hemisphere, and from the autumnal equinox to the winter solstice in astronomy. Meteorologists study phenology according to the following criteria: after the summer heat, the five-day average temperature is below 22 degrees for autumn, and it ends below 10 degrees.

The most obvious change in the natural landscape is in the trees. Many fallen leaves will be cleaned up in the city, and many tourists will flock to the mountains to see the red leaves.