Rain: Is it mizzling, grizzerable or siling down?

The Beaufort Scale was devised in 1806 to estimate wind speed by describing its effects, from zero - smoke rises vertically - to 12 - causing violence and destruction. After what seems like the wettest drought on record, BBC Radio 4's Broadcasting House has come up with its own scale to gauge the dampness of a British summer day, using colloquial terms suggested by its listeners. And presenter Kevin Connolly wonders why there are so few official terms to describe the rain .