A grade 1 hurricane will cause some crop damage but a grade 5 will gust at an alarming 175mph, hurling heavy debris through the air and wreaking mass destruction along its path

Where they occur: The USA, India and western Pacific

Occurrences per year: About 50

Size: 60 miles to 1,200 miles across and up to 10 miles high

Minimum speed: 74mph

Max speed: 175mph

Power: 1.6x10¹³ kW (8,000 times the amount of power generated in the USA in one day)

Casualties: Maximum casualties for a cyclone in Bangladesh in 1970 - 300,000 deaths

Hurricanes originate over Atlantic waters. If hurricanes begin over the western Pacific they are known as typhoons and in India they are called cyclones. Whatever its name, a hurricane always has the same characteristics: it is a huge swirling storm, which looks like a doughnut from above and brings very high winds, thunderstorms and torrential rain. A grade 1 hurricane can cause crop damage, but a grade 5 will gust at an alarming 175mph, hurling heavy debris through the air and wreaking mass destruction along its path.

Hurricanes form over large areas of warm water, above 26°C (80°F). Warm air rising from the sea condenses as it moves upwards, releasing latent energy to form a tropical cyclone. Typhoons tend to be stronger than hurricanes, because they pick up more energy as they travel across the Pacific, which is bigger than the Atlantic Ocean.