Is a sharp seasonal decrease in stratospheric ozone concentration that occurs over Antarctica in the spring. First detected in the late 1970s, the ozone hole continues to appear as a result of complex chemical reaction in the atmosphere that involves CFCs.

A large area over Antarctica discovered ten years ago to have a seasonal drop in stratospheric ozone concentration of as much as 50 percent. A similar hole has been found more recently over the Arctic. It is linked to the formation of stratospheric ice clouds that release chlorine atoms from chlorofluorocarbons during the Antarctic winter. The chlorine is present in quantities that cause extensive ozone depletion when the spring and summer sunshine return.

A well-defined, large-scale area of significant thinning of the ozone layer. It occurs over Antarctica each spring.

an area of the ozone layer (near the poles) that is seasonally depleted of ozone

a local weakening in the ozone layer of the atmosphere

Since the 1970's, the amount of ozone over Antarctica has dropped to about one third of normal levels during the spring. This depletion of ozone, believed to be caused by chlorine put into the atmosphere by man, is referred to as the ozone hole.

Widespread removal of total ozone in Antarctic spring. The hole is reaected in both the steep latitudinal gradients in the observed ozone depletion and in its temporal evolution since the mid-1970's.

observed depletion of the ozone layer over the Antarctic region that occurs yearly during the Southern Hemisphere spring. It is thought to be caused by the joint effects of human-made chlorine and bromine compounds and meteorological conditions that are specific to the region.

A growing hole in the stratospheric ozone layer appearing larger each year over the Antarctic for a few weeks in October.

Thinning break in the stratospheric ozone layer. Designation of amount of such depletion as a "ozone hole" is made when detected amount of depletion exceeds fifty percent. seasonal ozone holes have been observed over both the Antarctic region and the Arctic region and part of canada and the extreme northeastern United States.

A thinning break in the ozone layer. Designation of amount of such depletion as an "ozone hole" is made when the detected amount of depletion exceeds 50 percent. Seasonal ozone holes have been observed over the Antarctic and arctic regions, part of Canada, and the extreme northeastern United States.

a hole in the ozone layer that has recently been detected which allows the harmful rays to come through to earth. Hole has been attributed to reaction with chlorinated solvents.

refers to a region of the atmosphere over Antarctica where, during springtime in the Southern Hemisphere, up to three quarters of the stratospheric ozone disappears. Anthropogenic halocarbons are the primary cause of this phenomenon.

The extreme thinning of the ozone layer over Antarctica. The ozone hole is unique to Antarctica because of the polar vortex.

A thinning of the ozone layer over Antarctica, which occurs each spring.

A substantial reduction below the naturally occurring concentration of ozone, mainly over Antarctica.

A severe depletion of stratospheric ozone over Antarctica that occurs each spring. The possibility exists that a hole could form over the Arctic as well. The depletion is caused by a chemical reaction involving ozone and chlorine, primarily from human produced sources, cloud particles, and low temperatures.

Thin place in the ozone layer located in the stratosphere high above the Earth. Stratospheric ozone thinning has been linked to destruction of stratospheric ozone by CFCs and related chemicals. The 1990 Clean Air Act has provisions to reduce and eliminate ozone destroying chemicals' production and use. Ozone holes have been found above Antarctica and above Canada and northern parts of the United States, as well as above northern Europe.

massive loss of ozone from the lower stratosphere over Antarctica that occurs with the return of the sunlight each southern spring.