SUFFLAMINANDUS erat, Ben Jonson once remarked of William Shakespeare he was blown up out of all proportion, over rated. Much the same might be said of Jonson's namesake, Dr Samuel with the "h", who like Wagner, had wonderful moments, but some terrible quarters of an hour. "Rain", Johnson remarked to Boswell in one of his less riveting 15 minute pieces, "is good for the vegetables, and for the animals who eat those vegetables, and for the animals who eat those animals". But as we know, it is possible to get much too much of such a good thing.
Most parts of the west of Ireland collect 1,000 to 1,200 mm of rain in the average year, with around 2,000 mm being the norm in the Kerry, Donegal and Galway mountains. The eastern part of the country experiences falls between 750 and 1,000 mm, while a few places just to the north of Dublin have a little less. If the total Irish rainfall were evenly distributed over the island, the nationwide average would be about 1,150 mm - or sufficient to provide a layer of water slightly less than 4ft deep.
A fall of rain of 100 mm is equivalent to about 400 tons of water on every acre of ground. To put it in a more homely context, one could think of it almost of a million bath tubs full of water emptied onto a square mile of land. And when we realise that some of the wetter parts of Ireland have accumulated more than 200 mm of rainfall in the last two weeks, it is easy to see why some of our rivers find it difficult to cope.
Meteorologists classify rain, by the rate at which it falls, as "heavy", "moderate" or "light", each band being defined meticulously in terms so many millimetres per hour. Broadly speaking, however, moderate rain falls fast enough to form puddles very rapidly, light rain does not, and heavy rain is a downpour that makes a noise upon the roof, and gives a fine spray as each drop splashes on the wet surface of a concrete road.
Although at times you might not think so here in Ireland, the amount of water available to fall as rain is not unlimited. If all the water in the atmosphere at any time were to be extracted and poured upon the ground, it would form a layer only one inch deep around the world. This is equivalent to the average global precipitation for a period of about 10 days, so it follows that there must be a continual recharging of the atmosphere by evaporation to provide a steady supply of the raw material for our Irish rain.