The Four Climate Zones

The world has been divided into different climate zones. We have four main zones and two of these have sub zones. The basis of this division is variations in climate, vegetation, air pressure and the average temperature. The main zones are: arctic, temperate, subtropical and tropical.

There will of course be large local variations at times, so the strict geographic division is more of a guideline than a fixed rule. In addition to the main zones, we also have several minor zones, like the Mediterranean climate. In Norway where I am located, we have both arctic zones and several variations of the temperate zone.

Arctic Climate

In the arctic zone the average temperature in the warmest months of the year never exceeds 10 ˚C (50 ˚F). In these areas of the world, we also have permafrost, that is; the ground is frozen all year round. The low temperature and the permafrost, makes it impossible for vegetation with roots to live here. In addition, we often will find a high air pressure here: warm air rises and the cold air drops to the ground. Under these conditions, there will be no rainfall. We have two arctic climate zones, one around each of the poles on our planet.

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Temperate Climate

The temperate climate is locates south of the arctic area at the North Pole, and north of the arctic area at the South Pole. The temperate climate is one of the four climate zones, and it is located in a belt around the entire planet, both on the south and the north side. The gradual change between four seasons is very typical of this zone. The average temperature in the warm months of the year is around 10 ˚C (50 ˚F), and in the cold months it is -3 ˚C (26 ˚F).

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Here we find a varied vegetation with for example deciduous forests. We often experience a low air pressure in these areas. The cold air coming in from the arctic zone will rise and warm air flows in from the subtropic zone. There will also be a fairly high amount of rainfall in the temperate zones. We can split the zone in two: The warm temperate zone, which we find closest to the subtropic zone, and the cold temperate zone, which we find closest to the arctic zone.

Subtropical Climate

The subtropic climate is quite a bit warmer than the temperate climate. The average temperature in the warmest months is 20 ˚C (68 ˚F). In the coldest months of the year, the average temperature is 10 ˚C (50 ˚F). The summer is long and warm, the winter short and mild. Still there might be some days with frost in the winter. We find this climate in belts around the planet south of the northern temperate zone and north of the southern temperate zone, from latitude 30-40 to 27.

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Tropical Climate

The tropical climate is located around the equator to latitude 27, on both the north and south side. The average temperature in the tropic zone exceeds 18 ˚C (64 ˚F) in all the months of the year. In addition the seasons does not vary much around the year. In this climate zone we find three distinctive zones: tropical rainforest, tropical monsoon and savanna.

The tropical rainforest is very warm and moist with rainfall every day. The tropical monsoon climate has one very wet season with daily rainfall and one dry season where it hardly ever rains. And the savanna climate is characterized by drought and high temperatures.

If you want to learn more about gardening in a desert climate, you can head over to Growing In the Garden to learn the best practices.