Cyclones, Hurricanes, and Typhoons wreak havoc on coastal communities around the world, bringing severe winds, torrential rains and perilous storm surges.
These destructive storms are the most powerful weather events on Earth. They form along the equator over regions of warm seawater. As that warm, moist air rises, cold air rushes in along the surface of the ocean. This cycle repeats as more cool air is pulled in, warmed, and then rises up in a circular motion. Storms that form north of the Equator spin counterclockwise, while those that form south of the Equator spin clockwise, according to NASA.
Most scientists use the term tropical cyclone to describe a swirling, organized system of thunderstorms that has originated in tropical or subtropical waters and has closed, low-level circulation, according to the National Oceanic and Atmospheric Administration.
So, why do these storms have different names?
Location! Location! Location!
In the North Atlantic Ocean and Northeast and central North Pacific Ocean, they’re hurricanes. Hurricane season stretches from June 1 to November 30. According to NOAA, 97 percent of all tropical cyclone activity in the Atlantic occurs during this period.
In the Northwest Pacific Ocean, near Japan and the Korean peninsula, they’re known as typhoons. These storms can form throughout the year, but most develop between May and October.
In the South Pacific and Indian Ocean, a tropical cyclone is often just referred to as a cyclone. Like elsewhere in the world, these storms have mostly no official season, but peak between May and November.
How Does a Cyclone Become a Hurricane?
The short answer? Wind.
Tropical cyclones with sustained winds of less than 39 mph are called tropical depressions. Tropical storms have sustained winds between 39 mph and 74 mph. Once a tropical storm reaches sustained winds of more than 74 mph, it will be reclassified, depending on where it originates, as a hurricane, typhoon, or cyclone.
What about super-typhoons like Haiyan, which struck the Philippines in 2013? These storms can reach sustained wind speeds of more than 150 mph. Haiyan, which was one of the most powerful storms ever recorded, reached 195 mph. Hurricane Patricia, which spun along the west coast of Mexico in 2015 holds the record for highest wind speeds with sustained gusts of more than 200 mph.
Another barometer of a storm’s intensity is its atmospheric pressure. Measured in millibars, atmospheric pressure readings track changes in air pressure where masses of cold and warm air meet. In 1979, Typhoon Tip’s minimum central atmospheric pressure dipped to 870 millibars, the lowest reading ever recorded by these standards.
A Growing Problem
Hurricanes, typhoons and cyclones are graded differently. The intensity of hurricanes is measured using the Saffir-Simpson scale, which is based on wind speed and ranks hurricanes on a 1-5 scale. The wind speeds of typhoons, on the other hand, are monitored and measured using the designations, “typhoon,” “very strong typhoon,” and “violent typhoon.” Cyclones are classified in two ways—Australia uses a 1-5 ranking similar to the Saffir-Simpson and India uses monikers like “very intense tropical cyclone” and “super cyclonic storm,” according to the The New York Times.
Experts have said that climate change will impact different parts of the ocean in different ways but agree that, for the most part, the warming temperatures make these storms more severe and, in some cases, more frequent.
The number of Category 4 and 5 hurricanes the world saw between the 1970s and early 2000s nearly doubled, according to National Geographic. Storms are not only getting stronger, but they’re lasting longer, shedding more rain and moving more slowly. Wind speeds have picked up, too, by half in the last 50 years.
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