What causes Cyclones?

How a cyclone occurs

How a cyclone occurs
Reproduced with permission from BoM

The main source of energy for tropical cyclones is the warm oceans in the tropical regions. To initiate a tropical cyclone the sea-surface temperature generally needs to be above 26.5°C. However, existing cyclones often persist as they move over cooler waters.

The development of a tropical cyclone also relies on favourable broad-scale wind regimes and can persist for several days with many following quite erratic paths. They lose their source of energy when they move over land or colder oceans causing them to dissipate. Weakening may also occur if the cyclone moves into an unfavourable wind regime which disrupts the structure of the system. Sometimes a decaying tropical cyclone may interact with a weather system in higher latitudes to cause impacts far from the tropics.