The strong winds from a hurricane are known as tropical cyclones in some parts of the world, so you can expect them to sweep across the tropics. But there is one area of the tropics where hurricanes almost never form: the equator.
Historical maps of the locations of tropical cyclones (also called typhoons and hurricanes, depending on the location) would reveal that “it is extremely rare for them to form within a few degrees of the equator.” Gary Barnes (opens in a new tab), a meteorologist who is now retired from the University of Hawaii, told Live Science. (One degree of latitude covers approximately 69 miles or 111 kilometers.)
But why isn’t there hurricanes at the equator?
The reason has to do with the rotation of tropical cyclones, which is due to the rotation of the Earth. At the equator, even when the air is calm, the planet and the atmosphere above it are actually moving at over 1,000 mph (1,600 km/h), Barnes said. This movement follows the direction of rotation of the Earth from west to east.
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The Earth’s circumference is greatest at the equator. This means that anything on the equator moves east faster than anything far from the equator – anything on the equator travels a greater distance than anything is north or south of the Earth’s surface in the same amount of time.
If air moves north from the equator, it will also move rapidly east relative to its new surroundings. This means that air traveling north from the equator will appear to veer to the right. In contrast, air flowing south from the equator will appear to flow away to the left.
This phenomenon, known as the Coriolis effect, helps control the direction of rotation of tropical cyclones. In the northern hemisphere, air rotating to the right will create counter-clockwise rotational motion, and the reverse will occur in the southern hemisphere.
“Hurricanes collect rotation from the environment around them”, Paul Roundy (opens in a new tab)an atmospheric scientist at the University of Albany in New York, told Live Science.
This apparent wind rotation “is very weak near the equator but becomes much stronger as latitude increases,” Barnes said. That’s why tropical cyclones rarely form near the equator – higher latitudes have winds that turn faster to help tropical cyclones grow.
Still, “there are some weird exceptions,” Barnes noted. For example, in 2001, the South China Sea, Tropical Cyclone Vamei “intensified within 2 degrees of the equator, but the nascent circulation actually formed earlier, farther from the equator. “, did he declare. Scientists believe that winds interacting with the island terrain of the Indonesian archipelago may have generated the rotation that gave rise to Vamei, he said.
If a tropical cyclone crossed the equator, “it would begin to ingest air spinning in the opposite direction,” Roundy said. Barnes noted that this would likely cause the storm to weaken and collapse.
However, “it is conceivable that a storm could cross the equator for a small distance, since the opposite rotation remains quite weak near the equator,” Roundy said. “It is probably not possible for a tropical cyclone to cross several degrees of latitude into the opposite hemisphere.”
Climate change “doesn’t significantly affect Earth’s rotation, so it won’t directly impact the chances of a hurricane crossing the equator,” Roundy noted. “However, if rare low-latitude storms could reach higher intensities, if they moved towards the equatorial region, they could hold out better there. Climate change could increase the strength of the strongest storms.”
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