What Are Hurricanes or Typhoons? - dummies

What Are Hurricanes or Typhoons?

By Andrew Hollandbeck

Hurricanes and typhoons are types of tropical cyclones — large, rotating, low-pressure systems that bring rain and wind — with sustained wind speeds of over 74 miles per hour. These severe storms can spawn other weather problems, such as tornadoes and water spouts, flash floods, and dangerous thunderstorms.

Hurricanes and typhoons are the same weather systems; what they’re called depends on where they develop. A storm in the Atlantic Ocean or eastern Pacific Ocean — nearest to North America or Hawaii — that meets the criteria for rotation and sustained wind speed is known as a hurricane. The same sort of storm in the Indian Ocean or western Pacific Ocean — nearest to Japan, Hong Kong, the Philippines, or India — would be called a typhoon. Both are tropical cyclones.

Hurricane season in the Atlantic Ocean, which sees the most hurricane activity, is from June to November.

How are hurricanes or typhoons categorized?

Hurricanes are categorized based on the maximum speed of sustained winds within the cyclone. The Saffir-Simpson scale ranges from 1 for low-level hurricanes to 5 for the most unforgiving and catastrophic.

The Saffir-Simpson Hurricane Scale
Category Sustained Wind Speeds Expected Damage
1 74–95 mph Minimal: Damage to plants, signs, and unanchored mobile homes.
2 96–110 mph Moderate: Damage to roofs, serious damage to mobile homes, low-level flooding
3 111–130 mph Extensive: Damage to small buildings, low roads cut off, flooding
4 131–155 mph Extreme: Roofs destroyed, mobile homes destroyed, trees down, major flooding
5 156 mph or more Catastrophic: Most buildings and plants destroyed, major flooding

How are hurricanes and typhoons named?

Beginning in 1953, the (U.S.) National Hurricane Center maintained a list that it used to name tropical cyclones, including hurricanes. That list is now maintained by the World Meteorological Organization (WMO), which keeps separate lists for cyclones in the Atlantic, in the eastern north Pacific, and in the eastern central Pacific. Other organizations are responsible for naming cyclones in other parts of the world.

The lists for the Atlantic and eastern northern Pacific each actually comprise six different lists of 21 names that are used in rotation, which means that the names used for this year’s hurricanes will pop up again in six years. If more than 21 cyclones occur in the year, subsequent storms are named after the letters of the Greek alphabet.

When a hurricane is particularly devastating or costly, its name is removed from the list and replaced with a new one. There will, for instance, be no more hurricanes named Hugo (1989), Andrew (1992), Katrina (2005), or Irene (2011).

Until 1979, tropical storms and hurricanes were given only women’s names. Since then, they have been given alternating male and female names.