Wind

Highlights of Gary’s progress on the

Our Far South Expedition

March 1, 2012

Giant Petrol

Wind

At, 62° South, we appear to have no wind. Most unusual, but long may it continue. It means we get a bit of sea fog and can’t see very far, but what’s to see down here anyway but ocean and more ocean. In the South Island of New Zealand we’d be forgiven for thinking that the wind only ever blew from the West, sometimes a warm nor’west and sometimes a cold sou’west… but why is that? Well, atmosphere circulates around the globe and like the oceans it is driven by the temperature gradient from the poles to the equator and the fact the earth is spinning on it’s polar axis naturally subdivides the atmosphere into smaller cells of different temperature air circulating in opposing directions. Wind speed is greater at the boundaries of these air masses and in New Zealand this results in the Westerly Winds that we know so well in the south, in fact they were relied on by the big clipper ships that plied the southern oceans at the turn of the last century. In the Northern Hemisphere we have the Trade Winds. That’s great, but what will happen with a warming planet? Will the warm atmospheric cell over the tropic expand and push the westerlies south, resulting in a significant change to New Zealand’s climate? (there does seem to be some evidence of this already), or will the temperature gradient from equator to pole reduce and result in a weakening of the westerly system we know so well?

Still coming up …. global warming and CO₂