Ground level ozone forms from sunlight interacting with nitrous oxide. Nitrous oxide is a principle component of photochemical smog. A significant source of atmospheric sulfur comes from burning of sulfur-rich oil. Atmospheric CO2 increases during the Fall and Winter and decreases during the Spring and Summer. The average annual level of atmospheric CO2 is increasing today.
Aretes are sharp ridges eroded by glaciers.
The Pleistocene Ice Age reflects the gradual, long-term cooling of the Earth over geologic time 12. The existence of fjords is evidence that glaciers can erode well below sea 13. Glacial ice moves uphill during times of glacial retreat. Upper atmospheric ozone is created by lightning. Chlorofluorocarbons and methyl bromide breakdown in the upper atmosphere releasing Cl and Br, respectively, which in turn destroy ozone.