Monday, July 17, 2006

Glorious, glorious sunshine

A regular part of our life here in the west of Ireland is the six o'clock shipping forecast on the BBC, a daily litany of weather reports from stations around these islands -- Malin Head, Shannon, Valentia, Fastnet, etc. -- which my wife religiously listens to, although I never quite understood why. One of two reports will suffice for most of the time. "Wet almost everywhere with sunny intervals." or "Mostly dry with occasional showers."

It's all that warm water out there in the North Atlantic. The air moves across it from the west, soaking up moisture like a paper towel moving across a wet kitchen counter, to wring itself out on Ireland's west coast.

Geochemist Wally Broecker imagines a globe-spanning oceanic conveyor belt with its northern terminus near Iceland. Cold winds from Canada blow across the water there, cooling it. The cold, dense water sinks, and flows as a deep bottom current southward around the Cape of Good Hope into the Indian and Pacific oceans. There it rises, warms, and as a shallower current returns to the Atlantic and flows northwards.

Near Iceland, this water from a tropic sea finds its way to the surface where its heat is stolen away by Canadian winds. These are the balmy, moisture-drenched westerlies that warm and wet Ireland.

So, if Broecker is right, Ireland's green damp has its origin in palm-fringed oceans on the other side of the world.

But occasionally, every tenth summer or so, a high pressure ridge drifts up from the Azores and sits for weeks upon Ireland like a sunny crown. We are having a brilliant streak of grand weather now -- perfect for yesterday's Ventry Regatta.