The May 21st eruption of Iceland's Grimsvotn volcano sent a plume of sulfur dioxide into the atmosphere, and today that plume is swirling over the high latitudes of North America. A 5-day movie from the Global Ozone Monitoring Experiment-2 (GOME-2) onboard Europe’s MetOp satellite shows the SO2 in motion:
(video link)
http://www.spaceweather.com/swpod2011/26may11/so2.gif?PHPSESSID=r2if0hctap12nbkiprkunmjsp1