Hurricane Erin became the Atlantic Ocean’s first hurricane of the season – which runs from June 1 to November 30 – rapidly intensifying to Category 5 on Saturday before weakening to Category 2 on Tuesday.
While the storm remained far out at sea, it still generated major waves along the United States East Coast. Officials in North Carolina’s Outer Banks warned of coastal flooding and issued evacuation orders.
On its path were the northern Leeward Islands, Virgin Islands, Puerto Rico, Hispaniola, and the Turks and Caicos, with swells reaching the Bahamas, Bermuda, the US East Coast and Atlantic Canada.
The storm’s rapid intensification, reaching Category 5 in a short span, ranks it among the fastest-strengthening hurricanes ever recorded in the Atlantic. Scientists have linked such rapid intensification to climate change, as global warming increases atmospheric water vapour and ocean temperatures, providing hurricanes with more fuel to strengthen quickly and unleash heavier rainfall.
Storms that ramp up so quickly complicate forecasting and make it harder for government agencies to plan for emergencies.
The World Meteorological Organization (WMO) publishes an alphabetical list of names for upcoming tropical cyclones. These names are meant to be short, easy to pronounce, appropriate across languages and unique.
Erin was the fifth named storm of the season but became the first hurricane because the previous four storms never reached hurricane strength.
Are hurricanes, cyclones and typhoons the same thing?
When broken down to basics, yes, hurricanes, cyclones and typhoons are all essentially the same thing. The only thing that differs is where they originated from. All three are storm systems with winds exceeding 119km/h (74mph).
Hurricanes: Occur in the North Atlantic Ocean and Northeast Pacific, often affecting the United States East Coast, the Gulf, and the Caribbean. The strength of a hurricane is measured on a wind scale from 1 to 5. A Category 1 hurricane will bring with it sustained winds of 119-153km/h (74-95mph), whereas a Category 5 storm can exceed 252km/h (157mph).
Cyclones: Occur in the South Pacific and the Indian Ocean, often impacting countries from Australia all the way to Mozambique. Cyclone season typically runs from November to April.
Typhoons: Occur in the northwestern Pacific Ocean, frequently hitting the Philippines and Japan. Typhoon season is most common between May and October, but they can form year-round. The strength of a typhoon has various classification scales with the most severe storms named “super typhoons”.
How does a tropical storm form?
Tropical storms form over warm ocean waters near the equator. As this warm air rises, an area of lower air pressure is formed. As the air cools down again, it is pushed aside by more warm air rising below it. This cycle causes strong winds and rain.
When this cycle gains momentum and strengthens, it creates a tropical storm. As the storm system rotates ever faster, an eye forms in the centre. The eye of the storm is very calm and clear and has very low air pressure.
When winds reach speeds of 63km/h (39mph) the storm is called a tropical storm. When the wind speeds reach 119km/h (74mph) the storm becomes a tropical cyclone, typhoon or hurricane.
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