The UK is hit by fewer, less destructive tornadoes than the United States, but about 60 are recorded every year.

Scientists warn that the number of twisters in Britain is rising thanks to global warming.

The recipe for a tornado is a good thunderstorm, cold dry air above warm moist air, and winds running counter to each other.

As the updraft of air is struck by cross winds it starts to spin, and if this funnel reaches the ground it becomes a tornado which can lift dust and dead leaves - and occasionally small buildings.

A typical tornado is 100ft or so across, lasts less than ten minutes and has wind speeds of less than 110mph.

But in parts of the United States, where conditions are much more dramatic, they can last more than an hour, span up to one and a half miles wide and generate wind speeds of more than 200mph.

On average 80 people a year die in the US as a result of tornados.

Selsey, near Chichester, was hit in January 1998 by a 100mph tornado which caused £2 million of damage.

A bulldozer driver was almost ripped from his cab and astronomer Patrick Moore lost two of the three observatories in his back garden.

Forecaster Jeremy Plester said in Britain conditions for tornados are ripe only on about 11 days a year, and the vortices tend to be no more than a few metres in size and normally last less than half an hour.

He said: "People think tornados only happen in America, but they are actually reasonably frequent in this country.

"We have between 30 and 40 tornados every year in the UK but the big difference is that they tend to be smaller and do less damage.

"They often - but not always - occur in the southern part of Britain."

The strongest tornado ever recorded in Britain hit Plymouth in 1810. It was reported to have reached 213mph - a T8 rating.