What are the different tropical cyclones?
A tropical cyclone is the generic term for a non-frontal synoptic scale low-pressure system over tropical or sub-tropical waters with organized convection (i.e. thunderstorm activity) and definite cyclonic surface wind circulation. Tropical cyclones with maximum sustained surface winds of less than 39 mph are called tropical depressions. Once the tropical cyclone reaches winds of at least 39 mph they are typically called a tropical storm and assigned a name. If winds reach 74 mph, then they are called hurricanes.
