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Cyclones: Tropical and Temperate - Formation and Impact

July 19, 2026
5 min read

Cyclones: Tropical and Temperate - Formation and Impact

Introduction

Cyclones are large-scale atmospheric circulation systems characterized by low-pressure centres and rotating winds. They are classified as tropical cyclones (formed over warm tropical oceans) and temperate/extratropical cyclones (formed in mid-latitudes along fronts). Both types significantly influence weather and can cause devastating impacts.

Tropical Cyclones

Definition and Characteristics

  • Intense low-pressure system over warm tropical/subtropical oceans
  • Diameter: 100-2,000 km
  • Wind speed: Up to 300+ km/h
  • Central pressure: 900-990 mb (extremely low)
  • Structure:
    • Eye: Clear, calm, low-pressure centre (~30-60 km)
    • Eyewall: Ring of intense thunderstorms (highest winds and rainfall)
    • Rainbands: Spiral bands of convection extending outward

Naming by Region

RegionNameExamples
North AtlanticHurricaneHurricane Katrina
NW PacificTyphoonTyphoon Haiyan
Indian Ocean / Bay of BengalCycloneCyclone Amphan, Cyclone Fani
SW Pacific / AustraliaCyclone/Willy-WillyCyclone Debbie

Conditions for Formation

  1. Sea surface temperature > 27°C (deep warm layer to 60m)

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