What causes hurricanes?
Hurricanes start out as slow-moving tropical disturbances over warm ocean water.
File photo of car in hurricane (© Scott Smith/Getty Images)
Thanks to big storms such as Hugo and Katrina, hurricanes are household names, known for sweeping in death and destruction on winds capable of topping 150 mph. But unlike tornadoes, which strike quickly and with little notice, hurricanes usually takes days to form.
The huge, swirling storms start as tropical disturbances, when rain clouds build over warm ocean waters, generating wind speeds less than 38 mph. If the winds of the rotating storm are from 39 mph to 73 mph, it's labeled a tropical depression; at 74 mph, it officially becomes a hurricane.
Bing: What is a hurricane?
A hurricane's strength is based on its wind speed and ranked using the Saffir-Simpson Hurricane Scale. A Category 1 storm is dangerous, but a Category 5 storm is likely catastrophic, bringing winds faster than 157 mph. Hurricanes Hugo in 1989 and Katrina in 2005 were Category 5 storms. Though the high winds can be treacherous, the greatest threat during a typical hurricane is the storm surge, a wall of water that can be 100 miles wide and 15 feet deep and covers the coastline when a hurricane lands.
In the United States, the Atlantic hurricane season yields the biggest storms. It runs June 1 to Nov. 30 and primarily affects the coastal Southeastern United States, Caribbean islands and the Gulf of Mexico region. The East Pacific hurricane season starts in mid-May and affects western Mexico and Hawaii, though few such systems actually make landfall. The area known as Hurricane Alley — from eastern Texas around the Gulf of Mexico and Florida and up to the Northeast — is particularly susceptible.
Satellite image of Hurricane Michael (© NOAA/Reuters)
5 quick facts about hurricanes:
- The difference between a hurricane and a typhoon is simply where it happens. Both are tropical cyclones, called hurricanes in the Atlantic Ocean, Caribbean, and eastern Pacific Ocean, and referred to as typhoons west of the international date line in the Pacific Ocean.
- Names are given to tropical storms (which may or may not develop into a hurricane) in alphabetical order, alternating male and female names, and skipping names that start with the letters Q, U, X, Y and Z.
- It's a common myth that opening a window during a hurricane will help equalize the pressure in your home, but the reality is that doing so will only invite in more wind and debris.
- The deadliest tropical cyclone in history was Bangladesh's Great Bhola Cyclone in November 1970, which killed as many as 500,000 people.
- Superstorm Sandy, while destructive, was downgraded from hurricane status. Officially, it was Post Tropical Cyclone Sandy, but the superstorm name given by media outlets stuck.
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