Letter: Big as hailstones

Sir: Commenting on the association between hail and the Selsey tornado, William Hartston (Weather, 16 January) expresses surprise that measurement of hailstone size is disappointingly vague. He says that "the meteorological world is clearly in great need of an official scale for hailstone measurement".

Meteorologists already use millimetres and centimetres. Phrases such as "the size of golf balls" are handy for anyone who happens to be caught in a hailstorm without a ruler; and, of course, for the news media looking for a dramatic headline.

Moreover, a hailstorm intensity scale (from "pea" to "coconut") has been in use since 1986, when it was introduced by the Tornado and Storm Research Organisation, based at Oxford Brookes University.

DAVID PEDGLEY

Crowmarsh, Oxfordshire