Which months are the fall season

Divided in a meteorological sense, autumn in the northern temperate zone is from August 23 (heat stroke) to November 20 (light snow); in the southern temperate zone, it is from February 19 (rain in the northern hemisphere) to May 21 (light fullness in the northern hemisphere).

Fall is the harvest season, when many plants mature. In the subtropical regions of the Northern Hemisphere, temperatures drop significantly in the fall relative to the summer months. As temperatures drop, the leaves of many deciduous perennials will gradually change color, wither, and flutter off, leaving only their branches to survive the winter. And annual herbs will reach the end of their lives, withering to death throughout.

In the fall, the sun's altitude angle decreases and the temperature drops; the autumn breeze brings a refreshing breeze, the heat subsides, the fruit fills the branches, and the fields turn golden.

Extended information:

From the spring equinox through the summer solstice to the autumnal equinox, the Northern Hemisphere is in the summer half of the year, the Southern Hemisphere The Northern Hemisphere is in the summer and the Southern Hemisphere is in the winter half of the year. During this period, the northern hemisphere day is long and night is short, the southern hemisphere day is short and night is long; the North Pole is in the polar day, the South Pole is in the polar night; the sun's altitude north of the Tropic of Capricorn is always greater than the average, and south of the Tropic of Capricorn is less than the average. North of the Tropic of Cancer the sun rises on the northeast horizon and sets on the northwest horizon. The sun rises due east and sets due west across the globe on the second equinox.

From the autumnal equinox through the winter solstice to the vernal equinox, the northern hemisphere is in the winter half of the year, the southern hemisphere in the summer half of the year. During this period, the length of day and night, the extreme day and night, and the altitude of the sun in the northern and southern hemispheres are the opposite of those described above. North of the Tropic of Cancer, the sun rises on the horizon in the southeast and sets on the horizon in the southwest.

From the summer solstice to the winter solstice via the autumnal equinox, the northern hemisphere changes from half a year of summer to half a year of winter, and the southern hemisphere changes from half a year of winter to half a year of summer. During this period, the northern hemisphere day is shorter, the night is longer, the polar day zone is gradually shrinking; the southern hemisphere day is longer, the night is shorter, the polar night zone is gradually shrinking. The sun's altitude decreases north of the Tropic of Capricorn and increases south of the Tropic of Capricorn. North of the Tropic of Cancer, the direction of sunrise changes from northeast to southeast, and the direction of sunset changes from northwest to southwest. The autumnal equinox rises from due east and sets due west.

From the winter solstice through the equinox to the summer solstice, the northern hemisphere from winter half a year to summer half a year, the southern hemisphere from summer half a year to winter half a year. The length of day and night in the northern and southern hemispheres, the polar day and night, and the sun's altitude changes are the opposite of the above. North of the Tropic of Cancer, the sun rises from the southeast to the northeast and sets from the southwest to the northwest.

From the winter solstice to the vernal equinox and from the summer solstice to the autumnal equinox, the length of the day around the globe approaches the average (12 hours), and the extent of the extreme day and night gradually decreases. The sun's altitude north of the Tropic of Cancer and south of the Tropic of Capricorn are both approaching the mean. North of the Tropic of Cancer, the sun rises gradually closer to due east and sets closer to due west.

From the vernal equinox to the summer solstice and from the autumnal equinox to the winter solstice, the length of day and night around the globe is changing toward the extremes, and the range of polar day and night is gradually expanding. The sun's altitude north of the Tropic of Cancer and south of the Tropic of Capricorn also tends to be extreme. The direction of sunrise and sunset north of the Tropic of Cancer moves northeast and southeast and northwest and southwest, respectively.

Because of the complexity of the changes in day length and solar altitude between the Tropic of Cancer and the Tropic of Capricorn, occupying more space, we do not fully explain, the reader to summarize the law is not difficult to do. When analyzing, it is better to divide it into several stages.

For example, in the northern hemisphere, from the equinox to the sun is directly above the earth as a stage, and then to the summer solstice for the second stage, after the summer solstice to the sun again for the third stage, and then to the winter solstice as the next stage, from the winter solstice to the equinox is the last stage, the sun has completed a return to the movement.

There are large variations in the length of day and night, the altitude of the sun, the direction of the sun's rise and fall, and the direction of the sun at noon (for example, the sun is located north of the zenith at noon on the summer solstice in the northern hemisphere, and south of the zenith on the winter solstice) during each of these stages, and so on.

Reference:Autumn (Season)_Baidu Encyclopedia