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Hurricane Laura, a Category 4 storm, made landfall in southwestern Louisiana on Thursday with wind speeds reaching up to 250 km (150 miles) an hour.
What are hurricanes and how do they form?
- Tropical cyclones or hurricanes use warm, moist air as fuel, and therefore form over warm ocean waters near the equator. When the warm, moist air rises upward from the surface of the ocean, it creates an area of low air pressure below. When this happens, the air from the surrounding areas rushes to fill this place, eventually rising when it becomes warm and moist too.
- When the warm air rises and cools off, the moisture forms clouds. This system of clouds and winds continues to grow and spin. As such storm systems rotate faster and faster, an eye forms in the centre.
- Storms that form towards the north of the equator rotate counterclockwise, while those that form to the south spin clockwise because of the rotation of the Earth.
What is the difference between a hurricane, cyclone and a tropical storm?
- There is no difference. Depending on where they occur, hurricanes may be called typhoons or cyclones. As per NASA, the scientific name for all these kinds of storms is tropical cyclones.
- The tropical cyclones that form over the Atlantic Ocean or the eastern Pacific Ocean are called hurricanes and the ones that form in the Northwest Pacific are called typhoons.
- Tropical storms that form in the Bay of Bengal or the Arabian Sea are called cyclones.
How severe is Hurricane Laura?
- Hurricanes are categorised on the Saffir-Simpson Hurricane Wind Scale, which rates them on a scale of 1 to 5 based on wind speed. Hurricanes that reach category three or higher are classified as major hurricanes because of their potential to cause devastating damage to property and life.
- Hurricane Laura is a Category 4 storm, which means well-built framed houses can suffer severe damage with loss of most of the roof structure and exterior walls. A Category 4 storm has wind speeds between 130-156 mph and can uproot trees and bring down power lines.