What is the reason for the short spring and autumn in northern China?

Seasons are divided according to the changes of climate and the length of day and night. Everyone knows that the climate in Spring and Autumn is mild, hot in summer and cold in winter. If every three months in a year is defined as a season, then the number of days in each season is roughly the same, only one or two days apart, so there is no problem of the length of the season. However, due to the different positions of various places on the earth, some are in the south and some are in the north; Some are far from the sea, and some are very close; Some are plains, some are mountains; Some often blow in this direction, while others often blow in that direction. In this way, in the same period, the climate in different places is very different. For example, in June 65438+ 10, Harbin was covered with snow and ice, but what we saw in Guangzhou was red flowers and green leaves. In order to express the seasons with practical climatic significance, the temperature is generally used to divide the seasons. In China, the average temperature of each climate (five days in one climate) 10℃ is commonly used as the boundary temperature between cold and warm, and 22℃ is used as the boundary temperature between cold and warm. Winter is below 10℃, spring and autumn is between 10 ~ 22℃, and summer is above 22℃. According to this standard, four seasons are divided, and the length of the four seasons varies from place to place.

Spring in northern China is relatively short, usually less than two months. For example, the spring in Beijing is April 1 ~ 5 to May 2 1 ~ 25, in Shenyang it is April 2 1 ~ 25 to June10 ~/4, and in Harbin it is April 26 ~ 30 to June 20 ~ 24. It can be seen that in this area, when the stoves needed in winter are removed, the arbor needed in summer will soon be set up.

Since the season is determined by the temperature, the vertical speed of the temperature can determine the length of the season. In the north of China, the solar radiation is very weak in winter, and the exposure time is short. Cold air often flows from the north, and the temperature is very low. Since the coldest period of June+10 in 5438 passed, on the one hand, the solar radiation was gradually strengthened, on the other hand, the cold air force was continuously weakened, so the temperature gradually increased and the weather gradually became warmer, but the precipitation was scarce and the air was dry. After March, due to the further strengthening of solar radiation and the further weakening of cold air, the ground temperature can rise rapidly. Therefore, generally speaking, the temperature rise is the largest in March-April in northern China, that is, the temperature rise in April is obviously higher than that in March. For example, the average temperature in Beijing in March was 44℃, when the weather was still cold, and in April it was 132℃, which turned into a spring season.

In spring, there is still not much precipitation in this area. It's sunny most of the time, the air is dry, and the solar radiation continues to strengthen. The heat absorbed by the ground naturally increases rapidly, and the temperature also skyrockets. After less than two months, summer began. For example, the average temperature in Beijing reached 202℃ in May and rose to 242℃ in June. So the spring in the north is generally shorter.

In the same way, as the hottest period in July passed, the solar radiation gradually weakened and the cold air force continued to increase, so the temperature gradually decreased, and the maximum decline was from 10 to1. For example, in Beijing, the average temperature 125℃ in June 5438+ 10, and it dropped to 40℃ in June 5438+10, which is already a cold winter season.

Generally speaking, the spring and autumn in the north of China are particularly short, mainly because of the high latitude there, and winter comes early and goes late. Because the winter in the mid-latitude zone in the northern hemisphere is longer than that in the southern hemisphere.