Why do we have different climates across Australia?
07 September 2018
If you're travelling across Australia, you'll notice a huge variety in our terrain. The deserts around Alice Springs are different to the tropical wetlands of Kakadu or the temperate rainforests of Cradle Mountain. So why do these regions look and feel so different?
The reason we have so many different environments is that Australia covers a large range of climate zones. These are regions of the world that experience similar temperature and rainfall. The location of climate zones is largely determined by the sun.
Areas near 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, causing it to rise. The warm air cools as it rises, and the water in the air condenses and falls as rain.
It makes sense then that the tropical zone, which includes places like Cairns and Darwin, is warm and humid most of the year, with a clear wet and dry season as the tropical rain belt shifts south and then north of the equator.
If you move further away from the equator, you enter the subtropical zone. This is where the warm rising air air from the tropics falls as dry, cooler 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. Summers are hot, winters are mild and this zone is where you’ll find most of the world's deserts.
The next climate zone is the temperate zone. The Earth is round, so sunlight hits these areas on more of an angle then at the equator. The same amount of energy then has to cover a larger area so it’s cooler here than in the tropics.
The Earth is also tilted, so as we move around the sun during the year, temperate zones receive less direct sunlight in winter and more in summer.
Places in the temperate zone—like Hobart and Melbourne—therefore have distinct seasons, with 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.
The coldest climate zone is the polar zone. Here, the sun is lower in the sky and its rays reach Earth at an even larger angle.
The polar zone is very cold and cold air can't hold much moisture. Some areas in the Arctic and Antarctica are as dry as the subtropical deserts!
Australia’s climate zones
In Australia we are lucky enough to experience the tropical zone in the north, the subtropical zone across much of our centre, and temperate zones in the south.
Other features like mountains ranges and distance from the sea make things more complicated. The Great Dividing Range helps the temperate zone reach up along the east coast of New South Wales for example. Our red centre is mainly classified as desert, while coastal regions at a similar latitude are considered subtropical in the east and grassland in the west because of the different oceanic influences.
Image: The locations of Australia's climate zones are influenced by features such as mountain ranges and proximity to the sea.
There are many different methods used to define climate zones, depending on what you’re interested in. You can break the climate zones down into multiple sub-zones based on thresholds of temperature, humidity, and rainfall, or using the type of vegetation that grows in a region.
Regardless of how you define them, Australia is one of only a few countries in the world to span several climate zones. So be sure to make the most of it.
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