Tropical cyclone

A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its location and strength, a tropical cyclone is called a hurricane (), typhoon (), tropical storm, cyclonic storm, tropical depression, or simply cyclone. A hurricane is a strong tropical cyclone that occurs in the Atlantic Ocean or northeastern Pacific Ocean. A typhoon is the same thing which occurs in the northwestern Pacific Ocean. In the Indian Ocean and South Pacific, comparable storms are referred to as "tropical cyclones". In modern times, on average around 80 to 90 named tropical cyclones form each year around the world, over half of which develop hurricane-force winds of 65 kn (120 km/h; 75 mph) or more. Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through the evaporation of water from the ocean surface, which ultimately condenses into clouds and rain when moist air rises and cools to saturation. This energy source differs from that of mid-latitude cyclonic storms, such as nor'easters and European windstorms, which are powered primarily by horizontal temperature contrasts. Tropical cyclones are typically between 100 and 2,000 km (62 and 1,243 mi) in diameter. The strong rotating winds of a tropical cyclone are a result of the conservation of angular momentum imparted by the Earth's rotation as air flows inwards toward the axis of rotation. As a result, cyclones rarely form within 5° of the equator. South Atlantic tropical cyclones are very rare due to consistently strong wind shear and a weak Intertropical Convergence Zone. In contrast, the African easterly jet and areas of atmospheric instability give rise to cyclones in the Atlantic Ocean and Caribbean Sea.

Heat energy from the ocean acts as the accelerator for tropical cyclones. This causes inland regions to suffer far less damage from cyclones than coastal regions, although the impacts of flooding are felt across the board. Coastal damage may be caused by strong winds and rain, high waves, storm surges, and tornadoes. Climate change affects tropical cyclones in several ways. Scientists have found that climate change can exacerbate the impact of tropical cyclones by increasing their duration, occurrence, and intensity due to the warming of ocean waters and intensification of the water cycle. Tropical cyclones draw in air from a large area and concentrate the water content of that air into precipitation over a much smaller area. This replenishing of moisture-bearing air after rain may cause multi-hour or multi-day extremely heavy rain up to 40 km (25 mi) from the coastline, far beyond the amount of water that the local atmosphere holds at any one time. This in turn can lead to river flooding, overland flooding, and a general overwhelming of local water control structures across a large area.

Tables

Tropical cyclone basins and official warning centers · Formation › Formation regions and warning centers

Northern Hemisphere

Basin

Northern Hemisphere

North Atlantic

Basin

North Atlantic

Warning center

United States National Hurricane Center (Miami)

Area of responsibility

Equator northward, African Coast – 140°W

Eastern Pacific

Basin

Eastern Pacific

Warning center

United States Central Pacific Hurricane Center (Honolulu)

Area of responsibility

Equator northward, 140–180°W

Western Pacific

Basin

Western Pacific

Warning center

Japan Meteorological Agency

Area of responsibility

Equator – 60°N, 180–100°E

North Indian Ocean

Basin

North Indian Ocean

Warning center

India Meteorological Department

Area of responsibility

Equator northwards, 100–40°E

Southern Hemisphere

Basin

Southern Hemisphere

South-WestIndian Ocean

Basin

South-WestIndian Ocean

Warning center

Météo-France Reunion

Area of responsibility

Equator – 40°S, African Coast – 90°E

Australian region

Basin

Australian region

Warning center

Indonesian Meteorology, Climatology, and Geophysical Agency (BMKG)

Area of responsibility

Equator – 10°S, 90–141°E

Papua New Guinea National Weather Service

Basin

Papua New Guinea National Weather Service

Warning center

Equator – 10°S, 141–160°E

Australian Bureau of Meteorology

Basin

Australian Bureau of Meteorology

Warning center

10–40°S, 90–160°E

Southern Pacific

Basin

Southern Pacific

Warning center

Fiji Meteorological Service

Area of responsibility

Equator – 25°S, 160°E – 120°W

Meteorological Service of New Zealand

Basin

Meteorological Service of New Zealand

Warning center

25–40°S, 160°E – 120°W

Basin	Warning center	Area of responsibility	Notes
Northern Hemisphere
North Atlantic	United States National Hurricane Center (Miami)	Equator northward, African Coast – 140°W
Eastern Pacific	United States Central Pacific Hurricane Center (Honolulu)	Equator northward, 140–180°W
Western Pacific	Japan Meteorological Agency	Equator – 60°N, 180–100°E
North Indian Ocean	India Meteorological Department	Equator northwards, 100–40°E
Southern Hemisphere
South-WestIndian Ocean	Météo-France Reunion	Equator – 40°S, African Coast – 90°E
Australian region	Indonesian Meteorology, Climatology, and Geophysical Agency (BMKG)	Equator – 10°S, 90–141°E
	Papua New Guinea National Weather Service	Equator – 10°S, 141–160°E
	Australian Bureau of Meteorology	10–40°S, 90–160°E
Southern Pacific	Fiji Meteorological Service	Equator – 25°S, 160°E – 120°W
Southern Pacific	Meteorological Service of New Zealand	25–40°S, 160°E – 120°W

Season lengths and averages · Interactions with climate

North Atlantic

Basin

North Atlantic

Seasonstart

June 1

Seasonend

November 30

Tropicalcyclones

14.4

Eastern Pacific

Basin

Eastern Pacific

Seasonstart

May 15

Seasonend

November 30

Tropicalcyclones

16.6

Western Pacific

Basin

Western Pacific

Seasonstart

January 1

Seasonend

December 31

Tropicalcyclones

26.0

North Indian

Basin

North Indian

Seasonstart

January 1

Seasonend

December 31

Tropicalcyclones

South-West Indian

Basin

South-West Indian

Seasonstart

July 1

Seasonend

June 30

Tropicalcyclones

9.3

Australian region

Basin

Australian region

Seasonstart

November 1

Seasonend

April 30

Tropicalcyclones

11.0

Southern Pacific

Basin

Southern Pacific

Seasonstart

November 1

Seasonend

April 30

Tropicalcyclones

7.1

Total:

Basin

Total:

Seasonstart

96.4

Basin	Seasonstart	Seasonend	Tropicalcyclones	Refs
North Atlantic	June 1	November 30	14.4
Eastern Pacific	May 15	November 30	16.6
Western Pacific	January 1	December 31	26.0
North Indian	January 1	December 31	12
South-West Indian	July 1	June 30	9.3
Australian region	November 1	April 30	11.0
Southern Pacific	November 1	April 30	7.1
Total:			96.4

Impact of climate change on the rainfall during some recent hurricanes according to World Weather Attribution. · Interactions with climate › Influence of climate change

Hurricane Katrina

The name of the hurricane

Hurricane Katrina