How Volcanoes Work

 Image Described in Caption
Ozone hole -- The region in blue is the hole of ozone depletion, which extended to a record 10.5 million square miles on Sept 19,1998. The previous record of 10.0 million square miles was set in 1996. The Antarctic "ozone hole" develops each year between late August and early October. Regions with higher levels of ozone are shown in red. Courtesy of NASA.