Tropical cyclone

Tropical cyclone
Name	Tropical cyclone
Synonyms	Hurricane, Typhoon, Cyclone
Classification	Weather system
Formed	Over warm tropical oceans
Dissipated	Over land or cold water
Fatalities	Variable
Areas affected	Tropical and subtropical regions

Tropical cyclone A tropical cyclone is a rotating, organized system of clouds and thunderstorms that originates over warm Atlantic Ocean, Pacific Ocean, Indian Ocean, or Southern Ocean waters and can produce extreme winds, rains, and storm surge. These systems are monitored by agencies such as the National Hurricane Center, the Japan Meteorological Agency, the Australian Bureau of Meteorology, and the India Meteorological Department and have been central to major historical events including Hurricane Katrina (2005), Typhoon Haiyan, and Cyclone Nargis. Research institutions like the National Oceanic and Atmospheric Administration and the European Centre for Medium-Range Weather Forecasts lead numerical modeling, while international initiatives such as the World Meteorological Organization coordinate naming and warning practices.

Overview

Tropical cyclones develop in warm ocean basins including the North Atlantic Ocean, the Eastern Pacific Ocean, the Western Pacific Ocean, the North Indian Ocean, the Southwest Indian Ocean, the Australian region, and the South Pacific Ocean. Regional terminology varies: storms reaching tropical-cyclone strength are called Hurricane in the Atlantic Ocean and Eastern Pacific Ocean, Typhoon in the Western Pacific Ocean, and Cyclone in the Indian Ocean and near Australia. Notable historical systems such as Hurricane Maria (2017), Typhoon Tip, Cyclone Tracy, and Hurricane Andrew illustrate variations in size, intensity, and societal impact. Monitoring and research depend on satellites like those in the GOES and Himawari fleets, reconnaissance aircraft operated by the United States Air Force Reserve and NOAA Hurricane Hunters, and surface observations from the Global Observing System.

Formation and Structure

Formation typically requires sea surface temperatures above about 26.5 °C, low vertical wind shear, atmospheric instability, high humidity in the mid-troposphere, and a pre-existing low-level disturbance such as a tropical wave or the monsoon trough. Early-stage disturbances can derive from phenomena including the African Easterly Wave, the Intertropical Convergence Zone, or remnants of frontal systems. Mature systems exhibit a warm core, organized convection, an eyewall surrounding a calm eye and spiral rainbands; classical cases include Hurricane Isabel and Typhoon Hagibis. Vertical structure and dynamics are explored in studies by institutions like Scripps Institution of Oceanography and Woods Hole Oceanographic Institution using tools such as dropsondes, Doppler radar from facilities like NEXRAD, and ocean buoys from the Global Tropical Moored Buoy Array.

Classification and Intensity Scales

Intensity is measured by maximum sustained winds, central pressure, and damage potential using scales linked to agencies: the Saffir–Simpson scale (used by the National Hurricane Center for the Atlantic Ocean), the Japan Meteorological Agency 10-minute wind standard, and regional categorizations by the Australian Bureau of Meteorology. Historical records reference intense events such as Hurricane Patricia (2015) and Typhoon Haiyan (Yolanda). Reanalysis projects by the International Best Track Archive for Climate Stewardship and research from the National Center for Atmospheric Research refine intensity estimates and trends.

Impacts and Hazards

Primary hazards include extreme winds, intense rainfall leading to inland and urban flooding, storm surge along coasts, and secondary effects such as landslides and vector-borne disease outbreaks. Catastrophic events include Hurricane Katrina (2005), which caused levee failures in New Orleans, Cyclone Bhola (1970), which produced massive storm surge in Bangladesh, and Typhoon Haiyan (2013), which devastated parts of the Philippines. Economic and societal consequences involve international responses from organizations like United Nations Office for the Coordination of Humanitarian Affairs, Red Cross and Red Crescent Movement, and national emergency agencies such as the Federal Emergency Management Agency. Coastal infrastructure examples include ports like Port of Miami and energy assets like offshore platforms in the Gulf of Mexico.

Forecasting and Warning Systems

Forecasting combines observations from satellites (e.g., GOES-R series, Himawari), reconnaissance flights by NOAA Hurricane Hunters, and numerical models run by centers such as the European Centre for Medium-Range Weather Forecasts, the UK Met Office, and the National Centers for Environmental Prediction. Operational products include track and intensity forecasts, watches and warnings issued by regional bodies like the National Hurricane Center and the Japan Meteorological Agency, and communication through media outlets such as BBC News, The Weather Channel, and national broadcasters. Advances in ensemble forecasting, data assimilation, and coupled atmosphere–ocean models have been driven by projects at the Geophysical Fluid Dynamics Laboratory and the National Center for Atmospheric Research.

Preparedness and Mitigation

Preparedness measures include land-use planning exemplified in regulations of cities like Miami, building codes implemented after events such as Hurricane Andrew, evacuation planning practiced in jurisdictions like Japan and Florida, and nature-based solutions including mangrove restoration in regions like Bangladesh and Philippines. Mitigation also involves international frameworks and funding mechanisms such as the Sendai Framework for Disaster Risk Reduction and disaster insurance instruments like the World Bank's catastrophe bonds. Community resilience efforts engage organizations including the Red Cross, local municipal authorities, and research partnerships with universities such as Massachusetts Institute of Technology and University of Tokyo.

Category:Weather phenomena