What are ozone holes?

Answer 1

The ozone hole is a natural occurance, that occurs once a year at each pole. The southern polar hole is larger than the northern polar hole due to Earth's current magnetic alignment. The *size* of the hole is what is of concern... and something that the affairs of Man can play a part in. The hole is not really a hole at all, but a thinning of the Ozone layer due to a lack of sun hitting that area. Without sunlight, ozone naturally reverts into O2, a more stable oxygen form. There is no actual hole, merely a thinner layer, with about 1/3 or so the summertime level of ozone.

Ozone decays naturally with time. With the axial tilt that Earth has, once each year (local winter) each pole stops receiving the UV-C that turns some oxygen into ozone. So the ozone starts decaying, and a hole forms. The only ozone the pole gets at this time, diffuses in from areas that are still receiving UV-C. So the ozone would be exceedingly thin at this time.

Add contaminants to the mix, and the amount of ozone drastically decreases. Water vapor (natural and Man-sourced), chlorine (most commonly Man-sourced, carried by CFCs), and bromine (most commonly natural, but likely some Man-sourced, carried form example in halon) all have shown abilities in depleting ozone.

The ozone hole was discovered by Joseph Farman, Brian Gardiner, and Jonathan Shanklin in 1985. But no reason to believe that it has not existed as long as Earth has had an ozone layer (to have a hole in), an axial tilt (for winter, loss of UV-C which makes ozone), and a magnetic field (to make one hole larger than the other).

The concentration of ozone at any point is a balance of incident UV-C from the Sun (both making and destroying ozone), UV-B from the Sun (destroys ozone when absorbed), time, and compounds that can accelerate the decay of ozone.

Another view:

Briefly:

The ozone hole is a thinning of the ozone layer that occurs mostly in Antarctica where four months of winter darkness create ideal conditions for the destruction. CFCs and similar man-made gases break down the ozone in the stratosphere.

More:

The hole in the ozone layer happens because the ozone in the stratosphere is destroyed by chlorine and bromine from halogen atoms. These atoms come from man-made halocarbon refrigerator gases (chlorofluorocarbons [CFCs], freons and halons) which are emitted at ground level but move up into the ozone layer. These gases all contain chlorine and bromine.

Ozone (O3) is formed when ultraviolet (UV) light strikes an oxygen molecule (O2), converting it into two oxygen ions (O). These oxygen ions (O) combine with other oxygen molecules (O2) to form ozone (O3). Later, another oxygen ion (O) will combine with the ozone molecule (O3) to form two oxygen molecules (O2). This is the natural ozone-oxygen cycle of the earth.

The ozone layer prevents the harmful ultraviolet B-waves (UV-B) from reaching the earth. Increased exposure to UV-B is thought to be responsible for increases in skin cancer, eye cataracts and damage to plants and plankton. Because of this the nations of the world in 1989 adopted the Montreal Protocol which bans production of CFCs, halons and other ozone-depleting chemicals.

The ozone hole happens during the spring in Antarctica (Sept to Dec). Polar Stratospheric Clouds (PSCs) form during the all-dark winter. When spring arrives and UV light appears again, crystals of ice and nitric acid in these clouds help to release the chlorine and bromine atoms from the halocarbon gases. These destroy the ozone. (A single chlorine atom can continue destroying ozone for up to two years, reacting with up to 100,000 ozone molecules.)

Answer 2

The atmosphere is divide into layers. One of those layes hold a lot of ozone, which acts as a shield for one type of radiation coming from the sun. Probably due to the release of certain gasses(mainly freon) the ozone layer is thinning out and pretty much disappearing in certain spots, which causes more radiation to reach the earth.

Answer 3

The ozone hole is not actually a hole in the ozone layer. It is actually the thinning of ozone molecules below a certain concentration. These molecules get depleted by Ozone depleting substances making their concentration below a certain level. This is defined as ozone hole.

Answer 4

A depleted area in the Ozone Layer. It is worse at the poles, especially the south.

Answer 5

Ozone depletion is the process where ozone holes are created in the ozone layer. It is caused due to the action of chloro-floro-carbons on the ozone molecule to break it down to oxygen.