Doing the twist

CHRIS TITLEY investigates.

AS you might expect, the York twister has whipped up a storm. Everyone who watched, awestruck, as it formed in the skies to the south-east of the city centre, or saw the picture on the front of yesterday's Evening Press, has been talking about it.

"It took your breath away," said Kevin Berridge, who took some impressive photographs of the twister . "It's one of those things you see on telly, but you don't expect to see them here."

The maintenance engineer for Trebor Bassett was gardening at his home in Nunthorpe Crescent, York, with wife Joanne and six-year-old daughter Chloe on Bank Holiday Monday afternoon.

"We happened to look up and it was just there. It had already formed.

"I ran in to get the camera and took a couple of pictures. In the second one it is beginning to break up.

"There was no rain until about half an hour afterwards - that downpour we had. It was still: there was no wind in our garden."

Chloe, he said, was frightened at the mention of the word tornado. But she soon calmed down after realising it wouldn't wreak the sort of havoc seen on television footage from abroad.

This is not the first occurrence of its kind this summer. At the end of May a twister was caught on film by Kevin Keld above his workplace in Pocklington.

"It wasn't frightening. It's one of those things that I feel fortunate to have seen - I feel we have been treated to something rather special," Kevin said,

Jeremy Plester, of PA Weather, concurred: "This is one of the most impressive tornadoes I have ever seen. These are fantastic photographs."

Then, just over a week ago, Malton pensioner Ron Handy could not believe his eyes when he saw something similar spinning over the sky above his house.

All this freak weather suggests North Yorkshire is fast becoming tornado country.

Except for the facts that these phenomena are neither freak, nor tornadoes.

That's according to some of Britain's leading tornado experts. Scientists at TORRO, the Tornado and Storm Research Organisation based at Oxford Brookes University, are working hard to destroy some of the myths surrounding this subject.

They say a tornado can only be classed as such if it is connected both to the cloud base in the sky and to land. Because what we saw on Monday did not touch the ground it is classed as a funnel cloud. A funnel cloud might develop into a tornado - but then again, it might not.

To call it a freak condition is wrong, firstly because it is natural and explicable within the rules of physics. Secondly, it is not that rare an event. In fact in 1973 an American researcher called Dr Fujita discovered that the United Kingdom had the highest frequency of reported tornadoes for its land size in the world, a fact which still stands today.

Tornadoes are very much a part of the British climate. On average, 33 tornadoes are reported each year. However, they are most frequently seen in the Midlands, Central-Southern England, South-Eastern England and East Anglia.

If they are that common, why haven't we all seen one? Judith Rhodes, a forecaster with the Leeds Weather Centre, explained the misconception.

"You get quite a lot per unit area. They're all very small and can occur in remote places so they're not really reported. If they don't do much damage you don't really hear about them," she said.

So what sets a twister twisting? The short answer is no one is certain. "You need a lot of instability in the atmosphere," Judith said. "You need a cloud that has the potential for thunder and lightning, and fairly reasonable temperatures on the ground."

That helps to explain why we have received reports of three funnel clouds recently over the North Riding.

"From the weather conditions that we have had it's not that surprising - there's been a lot of thunder and lightning over the country," she explained.

"But it's probably surprising that they have been so well seen by quite a lot of people. Not many people have actually seen one. I haven't."

We can't blame global warming for the strange sights in North Yorkshire's skies either. Hotter weather is unlikely to lead to more twisters in Britain - quite the reverse in fact, according to TORRO's research. Britain's hottest months have been dominated by high pressure, which is unsuitable for thunderstorm and tornado development. So any overall warming of the British climate may result in fewer thunderstorms and tornadoes.

Britain may lead the world in the number of tornadoes, but it's a case of quantity not quality. Our twisters fizzle out, while the ones in the US can flatten towns and send herds of cattle spinning into oblivion.

"Tornadoes form there because where that happens is in the American Mid-west. There you have got two huge air masses meeting," Judith said.

"Cold, dry air comes down from the north west and warm, moist air comes up from the south.

"When they meet, there's a lot of energy released. It creates a lot of instability; that's why you get the big, destructive ones."

We should count our blessings that British tornadoes are timid affairs. Last month seven people were killed and 38 more injured when a tornado devastated a campsite in the western Canadian province of Alberta.

And, according to the boffins at TORRO, Americas's greatest death toll from a single tornado was the "tri-state" tornado of March 18, 1925, which travelled 219 miles through Missouri, Illinois and Indiana, leaving 695 dead and 2,027 injured. However it is possible that more than one tornado was involved.

In his book, Tornadoes of the United States, Thomas P Grazulis records some of the bizarre things carried by twisters over the years. These include a rack of ties carried 40 miles and a flour sack found 110 miles from its mill, perhaps the longest distance ever recorded for an object weighing more than one pound. And 45,000 migrating ducks were reported killed by another tornado. Dead ducks fell from the sky 40 miles from their bird refuge.

Raining ducks? Now that's freak weather.

PICTURE: Sky at fright: Monday's twister in York, as caught on camera by Evening Press reader Kevin Berridge.