Forecaster Bill Giles tells Lord Smith: it's not a new kind of rain. It's completely normal He adds: "How on earth could we have appointed as chairman of the Environment Agency someone who so obviously doesn't understand basic meteorology [like] Lord Smith?" Lord Smith had been attempting to explain the growing risk of flooding in Britain in an interview with The Sunday Telegraph last week when he claimed that a new type of rain was rapidly filling up rivers and drains. He said: "Instead of rain sweeping in a curtain across the country, we are getting convective rain, which sits in one place and just dumps itself in a deluge over a long period of time." Speaking last night, Mr Giles, 73, said that he objected to convective rain being used as an excuse for the widespread damage caused by flooding in recent years. He said: "I was alarmed by the inaccuracy of his statement. It reminds me of the 1970s, when British Rail used to talk about the wrong type of snow. I would issue a warning about the cold weather the night before, and the next morning, I would still find that my train was late. Convective rain, Mr Giles explained, occurred when air rose rapidly, often on hot summer days, causing water vapour to collect into dense towers of cumulonimbus cloud that can be up to 30,000ft tall. In light winds, the clouds move little and so when such a large quantity of water droplets fall as rain, intense, thundery showers are produced over one location. Mr Giles" comments have been echoed by other meteorologists who have criticised Lord Smith, the former Labour culture secretary who was appointed chairman of the Environment Agency in May 2008. Professor Anthony Illingworth, from Reading University's meteorology department, said: "Britain has always had convective rain - you can find evidence that it was around hundreds of millions of years ago. You can see the fossilised effects of where lightning - which is associated with convection - once struck sand. There are little things called fulgurites that go into the ground where the lightning melted the sand, causing it to form glass. Philip Eden, The Sunday Telegraph's weather expert, also criticised Lord Smith's "fundamental error." He said: "Lord Smith is the chairman of the Environment Agency and therefore should know everything there is to know about rain and floods." Ian Liddell-Grainger, MP for west Somerset, which was particularly badly hit by flooding last year and where a pensioner died when his car was swept into a river in November, described Lord Smith's comments as "an insult to the intelligence" of people there. A spokesman for the Environment Agency insisted, however, that Lord Smith had simply been trying to explain that convective rain was becoming increasingly common. He said: "Lord Smith has consistently said that we are seeing increasing instances of convective rain. Heavier rain from convection naturally causes more flooding, and we may well see this type of rain more frequently.