What kind of season is autumn?

Autumn is one of the four seasons. Meteorologically, the autumn in the north temperate zone is from August 23rd (summer) to165438+1October 20th (light snow). Autumn in the south temperate zone is from February 19 (rain in the northern hemisphere) to May 2 1 (xiaoman in the northern hemisphere).

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.

phenology,bioclimatology

Autumn is the harvest season, and many plants mature in autumn. In the subtropical region of the northern hemisphere, the temperature in autumn is obviously lower than that in summer. As the temperature drops, the leaves of many deciduous perennial plants will gradually change color, wither and fall off, leaving only branches for winter. Panicum miliaceum will come to the end of his life, wither and die.

temperature

As can be seen from the date distribution map of beginning of autumn in China, Northeast China is the earliest place in beginning of autumn in eastern China. In autumn, the cold air in the north is constantly invading, but its power is not very strong. Autumn weather often forms in northern China, and continuous autumn rain often appears in West China. The temperature will gradually drop in autumn, but it is generally slower than in winter. Due to the difference of dry and wet conditions, there will be cold and rainy weather conditions or dry and cool weather conditions in different regions. In the cold late autumn, due to the large temperature difference between day and night, the water vapor transpiration during the day will condense at night, either dew or frost.

Extended data:

Division standard

Divide four seasons according to climate and average temperature. The index is that the average temperature is below 10℃ in winter, above 22℃ in summer, and 10~22℃ in spring and autumn respectively.

July to September in the lunar calendar, autumnal equinox to beginning of winter, September to 165438+ October in the solar calendar, and autumnal equinox to winter solstice in astronomy. In China, autumn begins in early autumn, passes through early autumn, Mid-Autumn Festival and late autumn, and finally ends in early winter.

The phenological standard studied by meteorologists is: after the intense summer heat, the average temperature for five days is stable below 22℃, which means that it enters autumn and ends when it is below 10℃.

References:

Baidu Encyclopedia-Autumn (Season)