Why is it that ozone hole is over antartica , even though we produce CFCs here in the human inhabitations?

Answer 1

The ozone layer lies well above the surface of the earth in the stratosphere, 20-30 km high. Ozone (03) is a VERY reactive chemical. The thickness of this layer varies over time, but the ozone drifts to fill in "holes" in the layer, so without an outside influence, it will be relatively uniform.

The solar wind is a stream of charged particles sent out constantly by the sun. It strikes the earth's magnetic field and is deflected to the poles. These charged particles find ozone very attractive (literally), as a reduction source. They combine with the ozone, producing an oxygen molecule and an oxide molecule (mostly water since most of the solar wind is singly ionised hydrogen). This eliminates some of the ozone, and is natural.

During the southern summer, the earth is tilted so the south pole is closer to the sun, and receives a greater portion of the solar wind. This causes the "hole" at the pole to grow (it shrinks again in winter). This is a natural occurrence.

Where CFCs enter into it is that they persist as they rise into the stratosphere (i.e. don't break down). They also find ozone attractive as a reduction source, and break down in its presence. This means there is less ozone to "drift" to fill in the hole as it forms. In other words, the whole ozone layer becomes thinner. Over time, the cumulative effect of CFC use is noticeable as a much larger hole in the ozone layer.

Answer 2

It has to do with the chemistry. The reactions that destroy the ozone hole are happening everywhere all the time, just really slow because in most places they are constrained to gas phase reactions.

However in Antarctica, it gets really cold, much colder even than the Arctic because of the presence of a continent (ocean currents transfer heat to the arctic and water has a larger heat capacity than land.) This extremely cold temperature allows for a phenomenon known as Polar Stratospheric Clouds (PSCs) which are essentially ice clouds in the stratosphere. These clouds provide a surface for chemicals to stick to and facilitate the reactions that cause the ozone hole.

Also of note is that a little bit of sunlight is also needed for the reactions to happen. The result is that the hole forms at the onset of spring.

For more information check out the Ozone Hole Watch website: http://ozonewatch.gsfc.nasa.gov/
and click on Ozone Facts at the top for a better explanation of what I tried to say here.

Answer 3

The depletion of ozone over the poles is caused chiefly by ozone reacting chemically with the substance called chloroflurocarbons or CFCs.They are used as propellants in aerosol cans,refrigerants,solvents and fire extinguishing agents.As they are very stable compounds, when released into the atmosphere,they are not broken down and eventually reach the stratosphere.In the statosphere,CFCs become irradiated by UV light and decompose rapidly releasing chlorine(or Bromine) which are the real ozone-killers.
But the depletion of ozone over Antartica is more than that of the Arctic.This rapid depletion over Antarctic appears to be connected with the extremely low temperature in the stratosphere.The lower temperature over the Antarctica is the coldest spot on earth.From June to September,cold winds blow around the region which prevent warmer air from entering.
The lowest temperature prevailing over Antarctica,leads to condensation of water and nitric acid to form 'Polar stratospheric clouds' .The ozone-decomposing chemical reactions are greatly reinforced by the presence of these cloud particles.Thus the rapid depletion of ozone layer over the Antarctic is due to the chemical reactions on the surface of cloud particles in the stratosphere.
Further,the arctic polar vortex is much weaker than the Antarctic,as arctic tempertaures are several degrees higher,and polar stratospheric clouds are less common over Arctic.

Answer 4

because the CFC's start to burn a hole over us and then the atmosphere automatically spreads out over it to stop it from going all the way through, but really its making it thinner and thinner; but if it didn' do that we all would be dead by now.