image showing the extent of the sulfur dioxide gas cloud from the eruption of Okmok Volcano. The large red mass is from the main explosive phase on 12 July at 2130 UTC and is at an estimated height of 50,000 ft above sea level. The north-south dimension of this cloud is about 850 miles. Current emissions from the volcano are at a lower altitude of approximately 30,000 to 35,000 feet. Other OMI data (not shown) indicate that volcanic ash is mixed with the sulfur dioxide cloud.