Kierador wrote:
I'm having a little trouble understanding the idea of holes in the ozone layer. How can a hole be formed in a gas?
First you must understand ozone chemistry. This starts with the Chapman mechanism
Ozone forming reactions:
Very high energy UV (less than 240 nm) radiation dissociates oxygen: O2 -> 2O
Oxygen atoms react with molecular oxygen (in the presence of a third body) to form ozone: O + O2 -[M]-> O3
Ozone destroying reactions:
UV radiation (240 320 nm) dissociates ozone: O3 -> O2 + O
Ozone reacts with atomic oxygen to reform molecular oxygen: O3 + O -> 2O2
So what we have is a dynamic balance between a number of fast reactions. Now there are other reactions that help cycle between O, O2, and O3. These can involve the species: H, OH, HO2; and NO, NO2, NO3; but also Cl, ClO, ClO2; and Br, BrO, BrO2 which is where CFCs come into play. It starts to get more complicated if you also consider species such as HOCl, Cl2O2, and ClONO2 but I think you get the picture.
CFCs transport Cl and Br into the stratosphere, most naturally occurring Cl is in highly water soluble forms and gets rained out before reaching the stratosphere (volcanoes and sea salt transported by exceptional thunderheads being the exceptions).
Now this by its self wouldnt be expected to form a hole, so here are the other factors. The polar regions experience a meteorological phenomena in which they are relatively isolated from the rest of the atmosphere (the polar vortex), this happens mostly during polar winter, and during this time there are lots of polar stratospheric clouds (PSCs) present. Isolated is important so ozone cant flow in and replenish the hole, polar winter because there is not enough UV to create more ozone to replenish the hole, and PSCs play the roll of converting many reservoir species (i.e. non-reactive species that contain Cl, H, NO, etc) back into reactive ones.
basketcase wrote
While decreasing ozone levels worldwide is making these holes larger over time, the primary reason these "holes" exist is because the planet's magnetic field channels solar radiation towards the poles. The large amount of radiation hitting the poles means more of that radiation gets through, making it appear as if the ozone in that area isn't doing its job.
No, solar radiation is basically unaffected by the planets magnetic field, only charged particles (such as the solar wind) respond to a magnetic field. Dont know where you got this explanation.
North King wrote
That, and the fact that gravity naturally draws the atmosphere towards the equator would help... Thinking of it as a skin of oil, since the ozone layer is thinning, it tries to cover as much up as it can, but since it's drawn to the equator, the poles are first to go. That's my theory, at least.
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