What is the astronomical climate zone?

Climatic zone is a zonal climate classification unit which is roughly parallel to latitude circle and distributed around the earth, and it is the largest climate regional unit on the earth. From low latitude to high latitude, climatic zones are distributed in a certain order. The division of climatic zones is determined by the most basic climate forming factor-solar radiation. Aristotle in ancient Greece once divided the earth's climate into five climatic zones, namely tropical zone, northern temperate zone, southern temperate zone, northern frigid zone and southern frigid zone, which are called astronomical climatic zones or geographical climatic zones. This ancient method of dividing climatic zones is only based on the height of the sun and the length of day and night, so it is also called solar climatic zones.

According to the solar climatic zones, the percentage of each climatic zone in the whole earth's total area is: tropical zone accounts for 40%, temperate zone accounts for 52%, and cold zone accounts for 8%.

Temperate zone is located in mid-latitude area, with large temperature gradient between north and south and great climate difference. Such a large area of temperate zone does not match the actual climate distribution. Therefore, the temperate zone is generally divided into three zones, namely subtropical zone, temperate zone and cold temperate zone. The equatorial windless area is where the air gathers. In addition to high temperature all the year round, it is rainy all the year round. The climate and plants are obviously different from other tropical areas, and the tropical area is too large, so the equatorial climate zone is drawn from the tropics, which only includes the area between the equatorial climate zone and the Tropic of Cancer. In this way, the climatic zones on the earth include equatorial zone, tropical zone, subtropical zone, temperate zone, cold temperate zone and frigid zone.

Because the earth's surface is actually uneven, the distribution of land and sea, topography and ocean currents all affect the climate, and there is no recognized boundary between the sub-regions divided above. In fact, the isotherm is not completely parallel to the latitude circle, and the climatic zone divided by the tropic of cancer and the polar circle is very different from the actual climate, especially in high latitudes; However, because this method is simple and can roughly reflect the distribution of biological phenomena on the earth, it has been used so far.