What is a climate zone?
Climate zones are regions of the world that share similar temperature and rainfall patterns.
The location of climate zones is largely determined by their distance from the equator. There are different ways to classify climate zones.
Australia's climate zones
In Australia, we experience:
- tropics in the north
- subtropics across much of the continent's centre
- temperate zones in the south.
Other factors like mountains ranges and distance from the sea play a part. For example, the Great Dividing Range helps extend the temperate zone along the east coast of New South Wales.
Much of Australia's interior is desert. Coastal regions at a similar latitude – distance from the equator – are subtropical in the east and grassland in the west. This is due to the different oceanic influences. There are warmer waters along the east coast and cooler waters along the west coast.
Video: Ask the Bureau: Why do we have different climates?
The location of these climate zones is largely determined by the Sun. Areas around the equator get direct sunlight all year round, meaning that at noon the sun is right overhead. This is called the tropical zone. When the sunlight hits the surface of the Earth or the ocean, it warms the air above it, causing it to rise. The warm air cools as it rises, and the water in the air condenses and then falls as rain. It makes sense then that the tropical zone, places like Cairns or Darwin, are warm and humid most of the year, with a clear wet and dry season as the tropical rain belt shifts south and north of the equator.
If you move further away from the equator, you enter the subtropical zone. This is where the air from the tropics falls as dry air. The sinking air makes for high pressure systems and clear skies at the Earth's surface, so the subtropical zone is fairly dry. Places like Longreach and Brisbane are considered subtropical. The summers are hot, the winters are mild, and the subtropics is where we currently have most of the world's deserts.
The next climate zone is the temperate zone. Because the Earth is round, sunlight hits these areas on more of an angle than at the equator. The same amount of energy then has to cover a larger area, which means it's cooler here than at the tropics. And because the Earth is tilted as well, as we move around the sun during the year, the temperate zones receive less direct sunlight in winter and more in summer. Regions in the temperate zone – like Hobart and Melbourne – therefore have distinct seasons, with cold, short days in winter and warm, long days in summer.
The coldest climate zone is the polar zone. Here, the Sun is lowest in the sky, and its rays and energy reach the Earth at an even larger angle. The polar zone is very cold and cold air can't hold a lot of moisture. Some areas in the Arctic and Antarctic are as dry as our subtropical deserts.
In Australia we're lucky enough to experience the tropical zone in the north, the subtropical zone across much of the centre, and temperate zone in our south. Other features such as our mountains ranges or how far places are away from the sea can make things a bit more complicated, and you can break these zones up into sort of subzones based on temperature, rainfall and vegetation that grows. The Great Dividing Range for example helps the temperate zone reach up along the east coast of New South Wales. Our Red Centre is mainly classified as desert, while coastal regions at a similar latitude are considered subtropical or grassland.
Australia is one of only a few countries that spans multiple climate zones, so be sure to make the most of it.
Tropical zone
Areas near the equator get direct sunlight all year round. At noon, the sun is high overhead. This is called the tropical zone.
When sunlight hits the Earth's land and oceans it warms the air. This causes the warm air to rise, cooling as it goes.
With more direct sunlight in the tropical zone, there is more energy available to heat the air and generate water vapour. The water vapour in the air condenses and can eventually fall as rain.
This means that the tropical zone, which includes places like Cairns and Darwin, is warm and humid most of the year. It has distinct wet and dry seasons as the tropical rain belt, including the Australian monsoon, shifts north and south of the equator.
Our tropical areas include an equatorial zone, which includes the Tiwi Islands, Torres Strait Islands and the very north-eastern tip of Australia.
Subtropical zone
The subtropical zone is further away from the equator. This is where the warm rising air from the tropics descends as dry, cooler air.
The sinking air creates higher surface pressure and favours clear skies. This means the subtropical zone is relatively dry.
Places like Brisbane and Alice Springs are considered subtropical. Summers are hot, winters are mild. Most of the world's deserts are in the subtropical zone. Surrounding our central deserts is a grasslands zone.
Temperate zone
The temperate zone is cooler than the tropics. The Earth is a sphere, so sunlight hits temperate zone areas on more of an angle than in the tropics near the equator. The same amount of energy then has to cover a larger area, so there is less heating near the surface.
The Earth's axis is tilted relative to its orbit. As the planet moves around the sun during the year, temperate zones receive less direct sunlight in winter and more in summer.
For this reason, places in the temperate zone – like Hobart and Melbourne – have distinct seasons. There are warm, long days in summer, and cold, short days in winter.
Most regions in the temperate zone also tend to receive more rainfall in winter than in summer.
Polar zone
The Australian Antarctic Territory is an example of the coldest climate zone. The sun is lower in the sky and its light reaches Earth's surface at an even greater angle.
Cold air can't hold as much moisture. This means some polar areas in the Arctic and Antarctica are as dry as the subtropical deserts.
Ways to classify climate zones
It's possible to classify climate zones in different ways, for different purposes.
For example, if you are designing a building, it could be helpful to classify climate based on temperature and humidity. This may help you to better understand cooling or heating requirements.
Our maps show 3 classifications for climate zones across Australia:
- temperature and humidity
- seasonal rainfall
- native vegetation.
Australia has 6 major climate zones using the Köppen classification, which is mainly based on native vegetation