North and South Carolina have been hit with catastrophic rainfall and flooding amidst tropical storm Florence, which was downgraded from a hurricane at the weekend.

But what is a hurricane - and how is it different from a cyclone or a typhoon?

Well technically they're all the same thing - large rapidly rotating storm systems that meteorologists call 'tropical cyclones'.

The 'tropical' part refers to where these storms usually form, over the relatively warm water of tropical seas. To become a tropical cyclone a storm has to have a sustained wind speed of more than 74mph.

The key to which term is used is all about location.

Hurricane is used if the storm originated in the Atlantic, Caribbean and northeast Pacific.

Typhoon is the term used in the northwest Pacific Ocean.

Cyclone is used in the South Pacific and Indian Oceans.

Classes of hurricane

Hurricane Ophelia approaching the Azores islands in the Atlantic Ocean (
Image:
AFP)

Hurricanes are split into one of five classes based on how strong the winds are, based on the 'Saffir–Simpson hurricane wind scale'.

Hurricanes of Category 3 or higher are considered to be major events, that have the potential to cause significant loss of life.

Category 1 hurricanes are described as "very dangerous winds that will produce some damage", with winds of 74-95mph.

Category 2 hurricanes are described as "extremely dangerous winds that will cause extensive damage", with winds of 96-110mph

Category 3 hurricanes will cause "devastating damage", with winds of 111-129mph. Officials warn of major damage to buildings and trees being snapped and uprooted.

Hurricane Katrina, which devastated the US Gulf coast in 2005 was officially a Category 3 hurricane when it struck, although much of the damage was caused by the storm surge - coastal flooding caused by the massive rise in water caused by the storm.

Hurricane Harvey batters Texas last year (
Image:
REX/Shutterstock)

Category 4 hurricanes are expected to cause "catastrophic damage", with winds of 130-156mph. In this case, officials warn of power and water outages lasting weeks and well built homes taking severe damage, including the loss of most roofs.

Hurricane Harvey - which struck southern Texas last year - was a Category 4 hurricane, and was the costliest tropical cyclone on record, with much of the insurance bill coming after major flooding in and around the major city of Houston. Experts have predicted the clean up operation for Harvey and later hurricane Irma could top £200billion .

Category 5 hurricanes are the most dangerous, and have winds of more than 157mph. Officials warn of homes being totally destroyed, power and water outages that could last months, leaving the area uninhabitable.

When Hurricane Irma struck the Caribbean and Florida in September last year, it was the most powerful hurricane ever recorded in the Atlantic, with winds of 185mph recorded on the island St Martin. The storm was so powerful it was picked up on earthquake monitors, and it sparked suggestions that a "Category 6" should be added to the scale.

In the North Pacific, the term 'super typhoon' is used to describe storms with winds of more than 150mph.

Does the UK get hurricanes?

Ex-hurricane Orpelia hits the UK (
Image:
Ventusky.com)

Not really. A hurricane is a defined meteorological feature of clashing temperatures found only in the warm, humid atmosphere of the tropics.

Britain was battered at the end of last year by the tail end of hurricane Ophelia, but by then it was officially a "post-tropical cyclone".

So the UK can be hit by hurricane-force winds, but they aren't technically hurricanes.

Ahead of the Great Storm of 1987, BBC weatherman Michael Fish famously said: "Earlier on today, apparently, a woman rang the BBC and said she heard there was a hurricane on the way . . . well, if you’re watching, don’t worry, there isn’t!"

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Technically, he was right: the 1987 storm was not a hurricane.

The deadly 1987 storm developed in the Bay of Biscay and was powerful enough to generate wind speeds that consistently topped 100mph.

But Fish’s casual delivery, and his failure to predict the storm’s savagery, meant that the people and infrastructures of southern Britain were spectacularly unprepared for what they were about to endure.

Why do we name hurricanes and storms?

Damage caused to Richard Branson's Necker Island after Hurricane Irma (
Image:
PA)

Simply, names are easier to remember than numbers. According to the WMO, they're far more relatable than technical terms, so make for better warnings and messages in the media.

It means people will take more notice, hopefully heightening the safety of the public. The idea is so that communities are best prepared.

There's also less of a chance of making errors when planning. If you name storms, rather than using latitude or longitude or other identification methods, it allows ships, coastal bases, and monitoring stations to efficiently and easily exchange information.

How storms are named

Richard Branson's home on Necker Island in the Caribbean was destroyed by Hurricane Irma (
Image:
PA)

Hurricanes and storms are chosen by way of an alphabetical list. It's worked through chronologically. In total, there are six lists which are rotated every six years.

Female names were always traditionally used, but male names came into play in 1979. There are 21 names on the Atlantic season list – Pacific storms, cyclones and typhoons go by different ones.

The letters Q, U, X, Y, and Z are never used.

It's not entirely random, either. Names are selected that are familiar to people in various regions.