Weather Wise

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Indy Lifestyle Online
Torrential rain has been falling in the South-west, leading to flood warnings in Devon and Cornwall. Even if you are caught in a storm, however, it is difficult to judge how much rain is falling.

It is curious how a small amount of rain can make you feel so wet. It has hardly stopped raining in Devon and Cornwall since the weekend and, in the far west of the region, more than 60mm of rain fell in 24 hours. That's about the average for the entire month at Kew.

Yet when you think about it, 60mm does not sound all that much: it's less than 21/2 inches - hardly a cupful. The average rate of rainfall, however, is only about 1mm an hour - which is about an inch a day if it doesn't stop raining at all. You really do need a downpour to produce 60mm. And that leads to a very surprising conclusion: We all know, from chilly experience, that 30 seconds in a downpour is enough to feel utterly soaked. Yet even if those 60mm in Cornwall all fell in one hour, that would imply a rate of 1mm a minute, which means that half a millimetre of rain is enough to soak you to the skin.

We shall all have a good chance to test this theory in the next few days. If the forecasters are right, there will be few places without rain for the rest of this week.

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