Ozone confucion

[confucius]

Much has been made of the apparent 'holes' in the stratospheric polar ozone layer and the increased risk to people and animals of increased exposure to harmful solar ultraviolet radiation in the regions immediately beneath the 'holes'.

 

Well let me see if I understand this. The ozone layer protects the Earth from a significant amount of harmful UV radiation. Ozone is a gas O3 composed of dimeric oxygen and free radical oxygen that is produced by... well by UV light acting on dimeric oxygen. So presumably the photons of UV light that hit oxygen molecules provide energy to disrupt the molecular bond and produce free radical atomic oxygen. This is pretty reactive stuff so I guess it links up rapidly with oxygen molecules to form good old ozone the protector.

 

Okay so we know 20% of the atmosphere is oxygen and that oxygen reacts with UV radiation, or ozone would not form right? So this ozone is pretty amazing stuff in that even relatively small amounts in the tenuous stratosphere provide protection from UV radiation that a full thickness atmosphere can not do.

 

And my point is? Well is ozone not the by product of oxygen molecules reacting with harmful UV rays. So are ozone molecules really big like the Queen Mary 2 or am I missing the point completely (again).

[insane_alien]

ozone molecules are only slightly bigger than a water molecule. the fact is that they are amazingly god at absorbing UV and re radiating it at lower wavelegnths.

 

The reaction that couses O2 to become O3 is only effective at the altitude of the ozone layer because it has the right conditions of pressure, temperature and intensity of UV light. there is enough to have a lot of ozone production but the the wavelegnths that destroy ozone(high energy UV and up) are sufficiently filtered out by the upper atmosphere for the ozone to stick around a whil.

[confucius]

ozone molecules are only slightly bigger than a water molecule. the fact is that they are amazingly god at absorbing UV and re radiating it at lower wavelegnths.

 

The reaction that couses O2 to become O3 is only effective at the altitude of the ozone layer because it has the right conditions of pressure' date=' temperature and intensity of UV light. there is enough to have a lot of ozone production but the the wavelegnths that destroy ozone(high energy UV and up) are sufficiently filtered out by the upper atmosphere for the ozone to stick around a whil.[/quote']

 

Sorry, my comment on molecular size was rhetorical.

 

What you are saying is kind of fuzzy. I guess the pressure in the stratosphere is very low, the temperature is dependent on molecular motion and the UV radiation is full spectrum (may be there are some absorbtion bands from the photosphere - I dont know). So for an oxygen molecule to recieve enough energy from a single photon of UV radiaton requires less energy than that of an ozone molecule to absorb the energy, re emitting a photon of lower frequency and presumably the remaining energy in the reaction produces heat. Is this the way it is?

[insane_alien]

Close. neither require any energy to absorb the photon. The ozone moleule is a resonant molecule which makes it pretty stable and disperses energy throughout the molecule quite quickly. this makes it good at taking a high energy photon(UV-B/C) and emmitting lower energy photons (IR, Vis, UV-A)