@ Qurratulain

Chief source of Global Warming is increased percentage of green house gases in the atmosphere. CFCs mainly relate to the phenomenon of destruction of Ozone layer. Destruction of Ozone layer is different issue than to the issue of Global Warming, though some interlinks between these two things do exist.

And yes,, as far as issue of Ozone layer destruction is concerned, the main credit goes to these CFCs because green house gases have little to do with Ozone layer destruction.

And Ozone layer is a shield against only excessive ultraviolet radiation... i.e. not against infrared. (see wikipedia with key term 'ozone').

The process of Global Warming, in brief, is that first short-wave light radiations strike with the surface of earth. The earth, then bounces back most of those striking short-wave radiations. But after having 'bounced back', those radiations are no more 'short-wave light waves', but have been changed into long-wave heat waves (i.e. infrared)...

It is due to the fact that whether waves would be short-wave or long-wave, would depend on the surface temperature of source of those waves.

If surface temperature of the source of radiations were much high (as high as 5000 degrees ... i.e. surface of sun), then waves would be short-wave light waves. But if surface temperature from where the same waves have been bounced-off, is much low (like surface temperature of earth), then those bounced-off waves would be long wave (infrared) heat waves.

Now see that light waves when bounced off by earth surface, would be turned into heat waves. It’s meaning is that we do not get 'heat' directly from sun. The source of 'heat' is the surface of our own earth, which changes the incoming light waves into out going heat waves. This thing is responsible for the fact that temperature reduces with the increase in altitude because high altitudes are far from the surface of earth, the source of heat. That’s why temperature of Murry is lower than that of Islamabad.

Secondly, the heat, which we feel, is not equivalent to those infrared waves in pure form. In order that our atmosphere be ‘heated’ there must be something in the atmosphere which can absorb and ‘store’ that outgoing infrared waves. Such things in the atmosphere are water vapors and other green house gases. These vapors and gases can absorb and store the out going infrared waves and our atmosphere is thus ‘heated’ in this way.

This process can be explained with the help of a simple example… Suppose you are sitting in a stationary car in open sunshine. It would not be too hot inside the car if glass windows are open… but if glass widows are shut down…. Then there would be too much heat inside car. It is so because incoming short-wave light waves can penetrate the glass window… but outgoing long-wave heat radiations cannot be escaped from the same glass window. So the resulting heat shall be stored inside the car. And this is exactly the green house effect……..!!!!!!!

The presence of green house gases in atmosphere plays the role of glass windows… If there are less green house gases, less outgoing waves be stored but if there is more quantity of greenhouse gases, then more heat (outgoing waves) shall be absorbed and stored by the atmosphere. Since the over-all percentage of greenhouse gases is on the increase, due to the activities of humans,,, so the global level of heat is also on the increase.

And CFCs or this greenhouse effect etc. would have no effect to the internal magma of earth… Magma is produced due to earth’s own internal heat… which is the result of radio-active decay inside the core of earth.,

But eruptions of volcanoes etc. would also increase the percentage of greenhouse gases in the atmosphere…

Thanks!

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