Hurricanes

Section 1What a hurricane is

A hurricane is an intense tropical cyclone — a huge rotating storm system with sustained winds of at least 119 km/h (74 mph). The same storm type is called a typhoon in the Pacific and a cyclone in the Indian Ocean — same thing, different name. Hurricanes form over warm tropical oceans and weaken once they move over land or cooler water.

Section 2How hurricanes form

Three ingredients are needed: 1) warm ocean water of at least 27°C to provide energy through evaporation, 2) moist warm air to fuel the rising columns, 3) low wind shear so the storm can organise vertically without being torn apart. A spinning low-pressure area develops, deepens, and if conditions hold, intensifies into a hurricane.

Section 3Structure: eye, eyewall, rainbands

Eye — calm centre, often clear sky, low pressure. Eyewall — ring of intense thunderstorms around the eye where the strongest winds and heaviest rain occur. Rainbands — spiral arms of thunderstorms extending outward, bringing heavy rain and gusty winds far from the centre. The whole system rotates anticlockwise in the Northern Hemisphere and clockwise in the Southern.

Section 4Saffir-Simpson categories

Category 1: 119–153 km/h, minor damage. Category 2: 154–177 km/h, extensive damage to roofs/trees. Category 3: 178–208 km/h, devastating damage ("major hurricane" begins here). Category 4: 209–251 km/h, catastrophic damage. Category 5: 252+ km/h, total roof failure and structural destruction. Each category step roughly multiplies destructive potential.

Section 5Impacts and the Caribbean

Damage comes from high winds, storm surge (sea pushed onto land), flooding rainfall, and landslides on hilly terrain. Hurricane season in the Atlantic/Caribbean runs from 1 June to 30 November, peaking August–October. Jamaica's Hurricane Gilbert (1988) and Beryl (2024) are well-known recent examples — both caused widespread destruction.