National Geographic: The Antarctic ozone hole reached its maximum single-day area for 2013 on Sept. 16. The ozone hole (purple and blue) is the region over Antarctica with total ozone at or below 220 Dobson units (a common unit for measuring ozone concentration).
Last year the hole in the ozone layer above Antarctica was surprisingly small. But don't get used to that, say atmospheric scientists. Rather than signaling a speedy recovery, the shrinkage was likely a sign of variable weather.
The ozone hole still has...