Tropical cyclones
How warm oceans power the most intense storms on Earth.
This explanation is written conservatively from textbook-level science and has not yet been reviewed by a meteorologist. Treat it as a draft.
The mechanism
Follow the chain: each step causes the next.
01
Warm ocean
Warm sea surface water — commonly cited as around 26.5 °C or more through a deep enough layer — supplies heat and moisture.
02
Moist air rises
Air over the ocean rises within a pre-existing disturbance, forming deep thunderstorms.
03
Condensation releases heat
As vapour condenses into cloud, it releases latent heat that warms the core of the system and lowers surface pressure.
04
Winds strengthen
Lower pressure draws in stronger winds, which extract more heat and moisture from the sea — a self-reinforcing cycle.
05
A spinning storm
Earth's rotation makes the inflow spin, producing an organised cyclone with an eye and eyewall.
Explore it
Step through the mechanism one stage at a time.
Step 1 of 5
Warm ocean
Warm sea surface water — commonly cited as around 26.5 °C or more through a deep enough layer — supplies heat and moisture.
In short
One phenomenon, several names
Hurricanes, typhoons and cyclones are the same phenomenon; the name depends on the ocean basin. They form over warm tropical oceans, but generally not right at the equator, where the Coriolis effect is too weak to start the rotation.
Deeper science
Open a section for more detail.
What helps or hinders them
Besides warm water, development is favoured by a moist middle atmosphere and weak vertical wind shear (little change in wind with height). Strong shear, dry air, cooler water and landfall all tend to weaken them.
The hazards
Damage comes from destructive winds, storm surge along coasts, and extreme rainfall that can cause flooding and landslides far inland. Intensity scales and naming conventions differ between the agencies responsible for each basin.
Related topics
Atmospheric rivers
Long, narrow corridors of water vapour that can deliver both vital water supply and flooding rain.
4-step mechanismDraftRead topic