Classification of world climate

Climate classification method

Climate classification is the process of dividing the global climate into several types according to certain standards. Belonging to the same type of climate, its climate elements all comply with the same specified range. Climatic classification schemes vary by purpose or discipline. It can be roughly divided into two types:

① Theoretical classification (also known as cause classification). Its focus is to divide climate according to the factors that form it, such as that developed by Alisov (Soviet scholar) based on air masses.

②Experimental classification methods (also known as empirical classification methods), such as the K?ppen distribution method based on plant distribution, the latitude anti-classification method based on low profits, and the moisture balance (referring to precipitation, A moisture classification method based on the balance of evaporation and seepage).

The basic types of global climate can be divided into equatorial rainy climate (also known as tropical rainforest climate), new wind humid climate (also known as tropical humid climate or temperate humid climate), temperate desert climate, temperate steppe climate, subtropical Polar continent climate and ice sheet climate, etc.

World climate types

Zhou Shuzhen believes that the classification of world climate should start from the genetic point of view, comprehensively consider various factors of climate formation, and at the same time, it should also start from the point of production practice and adopt methods related to human life. Classify elements closely related to production and construction. The names of climate zones and climate types should be determined by the climate conditions themselves. In accordance with the above principles, Zhou Shuzhen made appropriate modifications based on the Schaller climate classification method, mainly adding monsoon climate types, dividing the global climate into 3 climate zones and 16 climate types, and another category of highland climate

(1) Low-latitude climate

The climate at low latitudes is mainly controlled by equatorial air masses and tropical air masses. The main circulation systems that affect climate are the equatorial convergence zone, the Wacker circulation, trade winds, equatorial westerly winds, tropical cyclones and subtropical highs. The radiation balance of the earth-atmosphere system is extremely high throughout the year, so the temperature is high throughout the year. The average temperature in the coldest month is above 15-18℃, and the possible evapotranspiration of water throughout the year is above 130cm. This zone can be divided into 5 climate types, of which the tropical arid and semi-arid climate types can be divided into 3 subtypes.

1． The equatorial rainy climate is distributed within 5° to 10° south and north of the equator, with varying widths. It is mainly distributed in the Zaire River Basin in Africa, the Amazon River Basin in South America, and the area from Sumatra to Irian Island between Asia and Oceania. . The height of the sun at noon is very high here all year round, so there is a long summer and no winter. The average monthly temperature is 25℃-28℃, and the annual average temperature is around 26℃. The annual temperature range is generally less than 3°C, and the daily temperature range can reach 6 to 12°C. Since it is under the control of the equatorial air mass throughout the year, the wind is weak, dominated by convergent updrafts, and there are many thundershowers. Therefore, it is rainy throughout the year with no dry season. The annual precipitation is more than 2000mm, and the minimum monthly precipitation is more than 60mm. However, the interannual variability of precipitation is large, which is related to the changes in the position of the equatorial convergence zone.

2. Tropical maritime climate is distributed on the east coast of the mainland in the trade wind belt of 10° to 25° north and south latitude and on several islands in the tropical ocean. It is on the windward coast. Tropical marine air masses prevail throughout the year. The climate is oceanic. The average temperature in the hottest month is around 28°C, and the average temperature in the coldest month is between 18 and 25°C. The annual and daily temperature ranges are both small. . Since the east wind (trade wind) brings humid and hot oceanic air masses, in addition to convective rain and tropical cyclone rain, there is also a lot of orographic rain, and the precipitation is abundant. The annual precipitation is more than 1000mm, which is generally concentrated from May to October without significant changes.

3. The tropical dry and wet season climate is roughly distributed between 5° and 25° in the northern and southern hemispheres. When the height of the sun is low at noon, it is located under the trade wind belt, controlled by tropical continental air masses, and downdrafts prevail. This is the dry season. When the height of the sun is high at noon, the equatorial convergence zone moves in, and there are moist convergent updrafts, which is the rainy season. There is at least 1 to 2 months of dry season in a year. Evaporation is less than precipitation in the wet season. The annual precipitation ranges from about 750 to 1600mm, and the precipitation variability is very high. The temperature is high throughout the year, with the average temperature in the coldest month being above 16-18°C. At the end of the dry season and before the rainy season, the temperature is the highest, which is the hot season.

4. Tropical monsoon climate is distributed in the southeastern part of the Asian continent near the latitude of 10° to the Tropic of Cancer, such as southern Taiwan, Leizhou Peninsula and Hainan Island, Indochina, most of the Indian Peninsula, the Philippines, the northern coast of Australia and other places. The tropical monsoon is developed here, and the seasonal changes in wind direction are obvious throughout the year. When tropical continental air masses dominate, precipitation is scarce. When the equatorial air mass is controlled, there is abundant precipitation and a large amount of tropical cyclone rain. The annual precipitation is large, generally between 1500 and 2000mm, concentrated from June to October (Northern Hemisphere). It has high temperatures throughout the year, with the annual average temperature above 20°C and annual temperature ranges of around 3 to 10°C. Spring and autumn are extremely short.

5． Tropical arid and semi-arid climates are distributed in the center of the continent and the west coast of the continent in the subtropics and trade wind belts. In the southern and northern hemispheres, it extends north and south with the Tropic of Cancer as the center, and its average location is roughly between 15° and 25° latitude. Due to different drought degrees and climate characteristics, it can be divided into three subtypes: tropical arid climate (5a), tropical (west coast) foggy arid climate (5b) and tropical semi-arid climate (5c). 5a and 5c are the source of tropical continental air masses, with large annual and daily temperature ranges and extreme maximum temperatures. 5a is controlled by subtropical high pressure downdrafts all year round, so precipitation is very little.

5c is located at the outer edge of 5a. It is controlled by the subtropical high pressure for most of the year and is dry and dry. During the season when the sun is high, the equatorial low pressure trough moves in and there is convective rain, so there is a short rainy season. 5b is located on the west coast of the tropical continent, with cold ocean currents passing by. It is affected by the ocean subtropical high pressure downdrafts all year round. It is foggy and less rainy, with very little precipitation, but the temperature is cooler, and the annual and daily temperature ranges are small.

(2) Mid-latitude climate

This is a zone where tropical air masses and polar air masses compete with each other. The main circulation systems that affect climate include polar fronts, prevailing westerlies, extratropical cyclones and anticyclones, subtropical highs and tropical cyclones. The radiant energy balance in this zone changes greatly throughout the year, so the four seasons are distinct. The average temperature in the coldest month is below 15 to 18°C, and there are 4 to 12 months with an average temperature above 10°C. The possible evapotranspiration throughout the year is between 130 and 52.5cm. Non-periodic changes in weather and seasonal changes in precipitation are significant. Coupled with the large continental area in the mid-latitudes of the Northern Hemisphere, the climate in this zone is even more complex due to the thermal contrast between land and sea and the towering and massive terrain. This zone is divided into 8 climate types.

6. Subtropical arid and semi-arid climates are distributed on the high-latitude side of the tropical arid climate, about 25° to 35° north and south latitudes on the west coast and inland areas of the continent. It is formed under the action of subtropical high-pressure downdrafts and back-shore winds in the trade wind belt. Depending on the degree of drought, it can be divided into two subtypes: arid 6a and semi-arid 6b.

The 6a subtropical arid climate is characterized by few clouds, little rain, strong sunshine and extremely high summer temperatures. However, the cool season temperature is lower than that of type 5a, and the annual temperature range is larger than that of type 5a, reaching more than 20℃. There is a small amount of cyclonic rain in the cool season, and the soil water storage capacity is slightly larger than type 5a. The 6b subtropical semi-arid climate is located on the outer edge of zone 6a. The summer temperature is lower than that of type 6a, and the precipitation in winter is slightly more than that of type 6a.

7. Subtropical monsoon climate is distributed on the east coast of the subtropical Eurasian continent, centered about 30°N and extending about 5° to the north and south. This is a zone where tropical oceanic air masses compete with polar continental air masses. Summer and autumn are also affected by tropical cyclone activities. Therefore, summers are hot and humid, and winters are warm and dry. The average temperature in the hottest month is above 22°C, and the average temperature in the coldest month is above 22°C. It is about 0~15℃, and the annual temperature range is about 15~25℃. The precipitation is above 750~1000mm. Summer rains are more concentrated and there is no obvious dry season. The four seasons are distinct and the frost-free period is long.

8. Subtropical humid climate is distributed on the subtropical east coast of North and South America, Africa and Australia, approximately 20° to 35° north and south latitude. In winter, it is affected by polar continental air masses, and in summer, it is controlled by moist oceanic air masses flowing from the western edge of the ocean high pressure. Due to the small size of the continent, there is no monsoon climate. The temperature difference between winter and summer is smaller than that in the monsoon area, and the seasonal distribution of precipitation is more even than that in the monsoon area.

9. Subtropical summer dry climate (Mediterranean climate) is distributed in the zone between 30° and 40° on the west coast of the subtropical continent. Affected by the seasonal movement of the subtropical high, it is located within the center of the subtropical high or on its eastern edge in summer, and the airflow is sinking, so it is dry, less rainy, and sunny. In winter, the subtropical high moves to lower latitudes, which are controlled by westerly winds. Fronts and cyclones are frequently active, bringing large amounts of precipitation. The annual precipitation is about 300~1000mm. The temperature in winter is relatively warm, with the average temperature in the coldest month being around 4-10°C. Due to different summer temperatures, it is divided into two subtypes. 9a cool summer type, close to the coast of cold ocean currents, with cool, foggy summers and little rain. The average temperature in the hottest month is below 22°C, and the average temperature in the coldest month is above 10°C. 9b Warm summer type, far away from the coast, has dry and hot summers, the average temperature in the hottest month is above 22°C, mild and humid winters, and a slightly larger annual temperature range.

10． Temperate maritime climate is distributed in the zone of about 40° to 60° on the west coast of the temperate continent. Westerly winds prevail here all year round, controlled by temperate ocean air masses, and warm ocean currents pass along the coast. Warm winters and cool summers, the average temperature in the coldest month is above 0℃, and the average temperature in the hottest month is below 22℃. The annual temperature range is small, about 6-14℃. It is humid and rainy all year round, more in winter. The annual precipitation is about 750 to 1000mm, and it can reach more than 2000mm in windward mountainous areas.

11． Temperate monsoon climate is distributed in the east coast of the Eurasian continent at about 35° to 55°. The northerly wind prevails here in winter, which is cold and dry. The average temperature in the coldest month is below 0℃, and the temperature difference between the north and the south is large. The southeast wind prevails in summer, which is warm and humid. The average temperature in the hottest month is above 20°C, and the temperature difference between the north and the south is small. The annual temperature range is relatively large, and the annual precipitation is concentrated in summer. The precipitation distribution decreases from south to north and from the coast to the inland. The non-periodic changes in weather are significant. When a cold wave breaks out in winter, the temperature can drop by 10°C or even more than 20°C within 24 hours.

12. Temperate continental humid climate is distributed on the east side of the temperate maritime climate zone of the Eurasian continent and in the temperate zone east of 100°W in North America. Winter is controlled by polar continental air masses and is cold, with a small amount of cyclonic precipitation. In summer, due to the intrusion of tropical ocean air masses, there is more precipitation, but it is not as highly concentrated as in the monsoon area. The seasons here are distinct and the weather changes drastically.

13． Temperate arid and semi-arid climates are distributed in the central parts of the Asian and North American continents between 35° and 50°N.

Because it is far from the ocean or protected by mountain barriers, it is not affected by oceanic air masses and is under the control of continental air masses all year round. Therefore, the climate is dry, hot in summer and cold in winter, and the temperature ranges greatly from year to year. Due to different degrees of drought, it can be divided into two subtypes: temperate arid climate (13a) and temperate semi-arid climate (13b).

(3) High-latitude climate: Polar air masses and icy ocean air masses prevail in high-latitude climate zones. There is cyclone activity on the ice-ocean front. The radiation difference of the earth-atmosphere system here is negative, so the temperature is low and there is no real summer. The water vapor content in the air is small, the precipitation is small, but the evaporation is weak, and the annual evapotranspiration may be less than 52.5cm. This zone can be divided into three climate types.

14. Subpolar continental climate is distributed in the area of ??50°N or 55°N to 65°N. The annual evapotranspiration here may range from 35cm to 52.5cm. Winter is long, with at least 9 months of winter in a year. In winter, the night time is long, the height of the sun at noon is small, and there are cold and high pressure centers in the central and easterly areas of Eurasia. There are light winds and few clouds. The ground radiation cools violently. It is the strongest continent and has extremely low winter temperatures. The daylight hours are long in summer, the average temperature in July is above 15°C, and the annual temperature range is extremely large. There is very little precipitation throughout the year, concentrated in the warm season. There is less snow in winter, but evaporation is weak and melts slowly. It is covered with snow for 5 to 7 months every year. The snow thickness is about 600 to 700mm, and the soil freezing phenomenon is serious. . Due to the moderate temperature and certain amount of precipitation in the warm season, it is suitable for the growth of coniferous forests.

15. Polar tundra climate is distributed on the northern edge of North America and Eurasia, part of the coast of Greenland, and several islands in the Arctic Ocean. In the southern hemisphere, it is distributed in the Malvinas Islands (Falkland Islands), South Shetland Islands and South Orkney Islands. The possible annual evapotranspiration is less than 35cm. It is winter all year round, and the average monthly temperature is around 0°C to 10°C for only 1 to 4 months of the year. Its latitude is close to or within the polar circle, so the phenomena of polar day and polar night are obvious. Temperatures are low during the polar night, but the adjacent ocean is slightly warmer than the subpolar continental climate. The average temperature in the coldest month is between -20℃ and 40℃. The average temperature in the hottest month is around 1-5℃. In July and August, the nighttime temperature can still drop below 0℃. There is a certain amount of precipitation on the ice-ocean front, and the annual precipitation is generally around 200 to 300mm. It is less than 200 mm in inland areas, mostly dry snow, and rain or wet snow in warm seasons. Due to the high wind speed, snow and fog often form, visibility is poor, and the snow area on the ground is not large. The only natural vegetation is mosses, lichens and small shrubs, which form the tundra landscape.

16. Polar ice sheet climate is distributed in Greenland, the Antarctic continent and several islands in the Arctic Ocean. It is the source of glacial air masses and Antarctic air masses. It is severely cold all year round. The average monthly temperature is below 0℃, and it has the lowest annual average temperature in the world. There are long periods of extreme day and night throughout the year. The annual precipitation is less than 250 mm, which is all dry snow and will not melt. It accumulates over a long period of time to form a very thick ice sheet. There are strong winds all year round, cold winds and snow, and poor visibility.

(4) Plateau Mountain Climate

As the height increases in the highland zone, various climate elements also change, resulting in obvious vertical zonal characteristics of the alpine climate. In order to distinguish the climate affected by altitude from that affected by factors such as latitude, and because alpine climate is limited to a local scale, highland climate is classified as a separate category and is not included in the lowland classification system.

Alpine climate has obvious vertical zonality, which varies depending on the latitude and regional climate conditions of the mountain. Its characteristics are as follows:

(1) The differentiation of vertical climate zones in mountains varies depending on the latitude of the location and the height difference of the mountain itself. In low-latitude mountains, the foothills have an equatorial or tropical climate. As the altitude increases, surface heat and moisture conditions gradually change, and vertical climate zones occur one after another. . This change is similar to what occurs in the lowlands with increasing latitude. If the latitude of the mountains is higher, the differentiation of the vertical climate zones will be reduced. If the height difference in the mountains is small, the differences in the vertical climate zones will also be small.

(2) Mountain vertical climate zones have the "imprint" of the local climate type. For example, equatorial mountains have the characteristic of insignificant seasonal changes throughout the year from the foothills to the top of the mountain. Both Mount Everest and Changbai Mountain have monsoon climate characteristics.

(3) The differentiation of vertical climate in mountains in humid climate areas is mainly determined by thermal conditions. In arid and semi-arid climate areas, the differentiation of vertical climate in mountains is related to both thermal and moisture conditions. There is a close relationship. The dryness in such areas is greater at the foothills, and as the altitude increases, the dryness gradually decreases.

(4) The same mountainous area also has different vertical climate changes due to different local conditions such as aspect, slope, terrain relief, concave and convex, visible and hidden. Warm slopes and cold lakes in valleys are an example. The climate in the mountainous areas is indeed subject to "different weather within ten miles".

(5) The vertical climate zones in mountains are different in origin and characteristics from the horizontal climate zones that vary with latitude.