Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science. Read more from this special report: A Guide to Hurricanes.
He replies: "Hurricanes form both in the Atlantic basin, to the east of the continental U. Get smart. Sign up for our email newsletter. Sign Up.
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Continue reading with a Scientific American subscription. Locations that may be affected are the Caribbean, Bermuda, Central America including eastern Mexico, the eastern and Gulf coasts of the United States, and eastern Canada. Many of the hurricanes and tropical storms in this area move around the western periphery of the Bermuda high taking them east of the U. Most U. This is the second most active region for tropical cyclones in the world.
The hurricanes and tropical storms that form in this area mostly move into the open eastern Pacific Ocean. They can also affect western Mexico and the southern Baja. Recently this was seen as Hurriance Odile hit the southern Baja. Sometimes after developing they can move west and many days later affect Hawaii.
Northwest Pacific Ocean Typhoon season: All year. This is the most active basin in the world. Most typhoons form between July through November. The tropical cyclones that form here can affect the Philippines, Guam, southeast Asia including China and Taiwan , and Japan. Meteorologists have divided the development of a tropical cyclone into four stages: Tropical disturbance, tropical depression, tropical storm, and full-fledged tropical cyclone. When the water vapor from the warm ocean condenses to form clouds, it releases its heat to the air.
The warmed air rises and is pulled into the column of clouds. Evaporation and condensation continue, building the cloud columns higher and larger. A pattern develops, with the wind circulating around a center like water going down a drain.
As the moving column of air encounters more clouds, it becomes a cluster of thunderstorm clouds, called a tropical disturbance. As the thunderstorm grows higher and larger, the air at the top of the cloud column is cooling and becoming unstable. As the heat energy is released from the cooling water vapor, the air at the top of the clouds becomes warmer, making the air pressure higher and causing winds to move outward away from the high pressure area.
This movement and warming causes pressures at the surface to drop. Then air at the surface moves toward the lower pressure area, rises, and creates more thunderstorms. Winds in the storm cloud column spin faster and faster, whipping around in a circular motion.
When the winds reach between 25 and 38 mph, the storm is called a tropical depression. When the wind speeds reach 39 mph, the tropical depression becomes a tropical storm.
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