A hurricane and a typhoon are the same thing. Both are tropical cyclones, and the only difference between them is where in the world the storm happens. A storm of the same strength is a hurricane in the North Atlantic, a typhoon in the Northwest Pacific and simply a tropical cyclone in the Indian Ocean.
Hurricane Isabel, seen by satellite on Sept. 15, 2003. Credit: NOAA.
What a tropical cyclone is
Meteorologists use tropical cyclone as the general term for a rotating, organized system of clouds and thunderstorms that forms over tropical or subtropical waters and has a closed circulation near the surface.
From depression to hurricane
Tropical cyclones are named by the strength of their maximum sustained winds:
| Maximum sustained winds | Name |
|---|---|
| below 39 miles per hour | tropical depression |
| 39 miles per hour or more | tropical storm |
| 74 miles per hour or more | hurricane, typhoon or tropical cyclone, depending on where it forms |
Which name, where
| Where the storm forms | What it is called |
|---|---|
| North Atlantic, central North Pacific, eastern North Pacific | hurricane |
| Northwest Pacific | typhoon |
| South Pacific and Indian Ocean | tropical cyclone, whatever the wind speed |
What it takes to make one
A tropical cyclone needs a weather disturbance to start from, warm tropical ocean, moisture and relatively light winds. If those conditions last long enough, they combine into the violent winds, large waves, torrential rain and flooding the storms are known for. When a system has not yet met all of these conditions but is forecast to bring tropical storm or hurricane force winds to land within a day or two, it is called a potential tropical cyclone in the Atlantic basin and in the central and eastern North Pacific basins.
Hurricane season
In the Atlantic, hurricane season officially runs from June 1 to November 30, and ninety-seven percent of tropical cyclone activity falls in that period. But the dates are not a guarantee: hurricanes can and do form outside those six months.
Sources
Based on "What is the difference between a hurricane and a typhoon?" from NOAA's National Ocean Service, a work of the United States government in the public domain.
许可协议： CC0 1.0（公有领域） · 改编自 oceanservice.noaa.gov
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