The Patagonian experience is dominated by one thing: the wind. It is constant, incessant, and relentless. Windsocks at airports are permanently horizontal and the few trees that survive on the hillsides all point east. It doesn’t even have significant gusts or lulls; it just is.
When I was there in 2004 the wind made such an impression on me that I wrote the following in an email home.
It is very windy here. [...] It has reaffirmed my faith that the world is round, because if all this air wasn’t just doing a lap of Antarctica and coming back round again, then wherever it was coming from would surely have run out by now.
This week, I saw a great image that illustrates this concept beautifully, all thanks to a volcanic eruption in Chile.
The eruption at the Puyehue-Cordón Caulle began nearly a fortnight ago, on the 4th June, producing an impressive eruption column over 12 km high and depositing a thick blanket of pumice on the surrounding landscape (Nice image gallery on the BBC website). Since then, the finer-grained ash has been carried eastward on the wind, causing air travel disruption and pretty sunsets in South Africa, Australia, Tasmania, and New Zealand as it goes.
The image below is the output from a computer model simulation of the Puyehue-Cordón Caulle eruption plume. It was produced by the Meteorological Service of Canada, using their MLDP0 computer model. It shows the predicted distribution of the ash on Friday 17 June, with the cloud doing a lap of Antarctica and coming back round to Patagonia again. The usual caveats and uncertainties of plume modelling apply, especially with respect to concentration estimates, which are strongly dependant on the estimates of how much ash is being erupted per second. Consequently, they have published these maps for guidance only. [See also the first comments, below]
Especially cool is the animated version – click here to see it.