The weather in Rizhao in April

Nowadays, astronomical seasons and climatic seasons are generally combined to divide the four seasons:

In temperate regions of the northern hemisphere, March-May is generally spring, June-August is summer, September 9- 10/October is autumn165438+1October, and 12- February is winter.

In temperate regions of the southern hemisphere, September ~165438+10 is spring, June ~ August is summer, March ~ May is autumn, and June ~ August is winter.

Seasons are several time periods, among which the geographical landscape that appears periodically every year is very different. Different regions have different seasons. For temperate climate, especially in China, a year is divided into four seasons, namely, spring, summer, autumn and winter. For savanna, there are only dry season and rainy season. In the cold zone, not only winter, but also the North and South poles can be divided into four seasons.

Extended data:

The fundamental reason of seasonal variation is that the earth's rotation axis is not perpendicular to its orbital plane, and the deviation angle is 23 degrees and 26 minutes (the angle of ecliptic). In different seasons, the solar illumination received by the northern and southern hemispheres is unequal and changes periodically.

The sunny hemisphere is summer and the other half is winter. Spring and autumn are transitional seasons. When the direct point of the sun is close to the equator, the sunshine conditions in the two hemispheres are similar, but the trend of seasonal development is still opposite-when it is autumn in the southern hemisphere, it is spring in the northern hemisphere.

The division of astronomical seasons is determined strictly according to the position of the earth's revolution, but due to the climate, the actual seasons in different regions are different.

Seasons have two main characteristics, one is the periodicity of seasonal changes, and the other is the difference of seasons. There are great differences in climate in different seasons in the same area, mainly in temperature and rainfall. The main reason for these differences is the difference in sunshine. The change cycle of seasons is generally one year, so in China, a country with four distinct seasons, people often take seasons as the unit of time measurement between years and months. Although the boundaries of this seasonal change are not so obvious, the overall macro differences are still easy to be perceived and recognized.

China people believe that the four seasons have different characteristics, namely "spring", "summer", "autumn" and "winter storage". That is, everything grows in spring, grows in summer, harvests in autumn (mature) and hides in winter (animals hibernate and plants shed leaves).

Reference link: Baidu Encyclopedia-Season