cycloon

A cycloon, commonly written cyclone in many languages, is a large-scale atmospheric system characterized by a low-pressure center and inward rotating winds. The term covers several kinds of storms, most notably tropical cyclones and extratropical cyclones.

Tropical cyclones form over warm tropical waters when conditions include sea surface temperatures above roughly 26.5 °C, high humidity, and low vertical wind shear. They develop a organized circulation, with an eye at the center and an eyewall of intense convection; they can grow to hundreds of kilometers in diameter. Extratropical cyclones form outside the tropics and arise from baroclinic processes associated with weather fronts and jet streams; they can produce strong winds, heavy rain, and snow, and typically have asymmetric structure.

Classification and regional names vary: tropical cyclones are named and categorized by wind speeds; in the North Atlantic and some regions they are called hurricanes, in the western Pacific they are called typhoons, and elsewhere the generic term cyclone is used. The Saffir-Simpson scale classifies tropical cyclones into five categories based on sustained winds. Extratropical cyclones do not have a single global wind-based scale, but they are described by factors such as central pressure, wind field, and weather impacts.

Impacts and forecasting: cyclones can cause property damage, flooding, storm surge, and tornadoes. Forecasts rely on satellite data, radar, occasional reconnaissance aircraft, and computer models to predict track, intensity, and rainfall. Early warnings and evacuations reduce losses, and preparedness measures remain central to reducing risk.