The Difference Between Tropical Storms And Hurricanes

By Debra Kelly on Monday, December 30, 2013
“It was a dark and stormy night.” —Edward Bulwer-Lytton, “Paul Clifford”

In A Nutshell

Hurricanes and tropical storms are essentially much the same thing; they’re both weather phenomena that consist of a large, low-pressure system combined with strong winds to create a rotating wind storm. These systems are considered a tropical storm once wind speeds reach 63 kilometers per hour (39 mph), and a hurricane once winds reach a sustained speed of more than 119 kilometers per hour (74 mph). Both can create mass devastation once they make landfall.

The Whole Bushel

Tropical storms and hurricanes are different strengths of the same storm. They are created when a low-pressure system is coupled with strong winds, creating a cyclonic wind pattern that rotates counter clockwise in the northern hemisphere and clockwise in the southern hemisphere. These storms form over tropical or sub-tropical waters, but can move well outside of their formative areas.

The weather phenomenon is called a tropical storm when sustained wind speeds are between 63 and 119 kilometers per hour (39–74 mph). (Storms that are just beginning to form and meet all the other criteria for a tropical storm but haven’t yet gained the appropriate wind speeds are called “tropical depressions.”) When sustained wind speeds reach more than 119 kilometers per hour, the tropical storm turns into a hurricane.

Both types of storms can be covered by the generic term “tropical cyclone.” In fact, the term “hurricane” is also location-specific; only those storms in the North Atlantic Ocean, Northeast Pacific Ocean east of the Date Line, or the South Pacific Ocean are called “hurricanes.” A typhoon is a hurricane that’s in the Northwest Pacific Ocean west of the International Date Line. Hurricanes in the North Indian Ocean are called “very severe cyclonic storms,” while those in the Southwest Indian Ocean are simply known as tropical cyclones. When in the Southwest Pacific Ocean or Southeast Indian Ocean, they’re called a “severe tropical cyclone,” or “Category [X] cyclones.”

Tropical storms are simply called “tropical storms,” except in Australia; there, they’re classified as Category 1 cyclones.

Hurricanes become “major hurricanes” when sustained wind speeds reach more than 179 kilometers per hour (111 mph); they’re also grouped into categories (Categories 3, 4, and 5). The higher the wind speed, the higher the Category.

There is also a very specific type of hurricane called a “Cape Verde hurricane.” It’s named for the area where it forms, which is in or around the Cape Verde Islands. Generally, these storms gain strength and become tropical storms while still around the islands and then gradually move into the Caribbean; by the time they reach the Caribbean, they have gained enough strength to be classified as hurricanes.

When tropical depressions become tropical storms, they’re given a name to make referring to them easier than using the latitude-longitude coordinates that have been used while the storm is growing. The World Meteorological Organization has a list of male and female names, arranged alphabetically, that are repeated every six years. If a hurricane causes massive destruction and wide-spread devastation, the name is retired. (Recently retired hurricane names include Sandy, Irene, Igor, Tomas, and Katrina.)

When the process of naming storms began in the early 1800s, they were originally named after saints. By the middle of the 19th century, that had been changed to using only women’s names. Hurricanes and tropical storms weren’t given men’s names until 1978.

While the origins of the name “tropical storm” are pretty self-evident, you might wonder where the term “hurricane” came from. The Maya people had a creator god named Hurakan. According to legend, the Earth was once completely water, until Hurakan blew across the water and revealed the land. He also orchestrated the flood myth of the Maya. Hurakan later gave his name to the Caribbean god Hurican.

Show Me The Proof

NOAA: what is a hurricane, typhoon, or tropical cyclone?
NOAA: Tropical Cyclone Climatology
National Hurricane Center: Tropical Cyclone Naming History and Retired Names
NOAA: Cape Verde hurricane
The Weather Channel: Where Did That Weather Word Come From?