A rapidly rotating storm system with a low-pressure center, strong winds, and heavy rain, forming over warm tropical oceans.A tropical cyclone is a large, organized system of thunderstorms that rotates around a low-pressure center, known as the eye, and produces destructive winds and torrential rain. These storms form over warm ocean waters near the equator, where the sea surface temperature exceeds about 26.5°C (80°F). The heat and moisture from the ocean fuel the storm, which can grow to hundreds of kilometers across and last for days or even weeks. Depending on the region, tropical cyclones are called hurricanes (Atlantic and eastern Pacific), typhoons (western Pacific), or cyclones (Indian Ocean and South Pacific).
The understanding of tropical cyclones as rotating heat engines developed in the mid-20th century, with key contributions from meteorologists such as Herbert Riehl and Joanne Simpson, who proposed the 'hot tower' hypothesis in the 1950s.
Warm ocean water evaporates, and the moist air rises, creating an area of low pressure at the surface. As air rushes in to fill the low pressure, the Earth's rotation (the Coriolis effect) causes the incoming air to spiral, setting the storm spinning. The rising air cools and condenses, releasing latent heat that warms the upper atmosphere, further lowering pressure and intensifying the circulation. This positive feedback loop continues as long as the storm remains over warm water and encounters favorable wind conditions aloft. The storm's energy comes from the ocean's heat, not from a temperature contrast like mid-latitude storms.
Forecasting tropical cyclone tracks and intensity is critical for issuing warnings and evacuations, saving lives and reducing economic damage in coastal regions.
The eye of a tropical cyclone is often calm and clear, with light winds, because the air descends there, but the most violent winds and rain occur in the eyewall just outside the eye.





















