Hurricane, tropical storm and tropical depression: What’s the difference?

Tropical depressions form when a low-pressure area is accompanied by thunderstorms that produce maximum winds below 39 mph.

As for tropical storms, those are more severe. Depressions become storms when winds reach between 39 and 73 mph. They also must follow a cyclone pattern to become a storm.

Hurricanes are a step up from a tropical storm, with winds of more than 74 mph. Hurricanes are further rated into five categories based on their wind speed:

Category 1: 74-95 mph

Category 2: 96-110 mph

Category 3: 111-129 mph

Category 4: 130-156 mph

Category 5: above 157 mph

Credit: Chip Somodevilla

Credit: Chip Somodevilla

However, all three types of storms are fueled by warm, moist air near oceans in tropical areas.