Greenhouse effect

[MJKeulen]

Hello, I'm posting this for my 7 year old son, who asked me a question that I cannot answer, or find the answer to.

 

He wants an explanation for why the suns rays cannot escape once they enter our atmosphere, if they can get in in the first place they why can't they get out..??? We understand the greenhouse gases preventing the heat from escaping but why would they stop the heat from getting in in the first place. If someone can give us a clear answer I would appreciate it.

 

thanks for you time.

 

Mandy

[Moontanman]

Hello, I'm posting this for my 7 year old son, who asked me a question that I cannot answer, or find the answer to.

 

He wants an explanation for why the suns rays cannot escape once they enter our atmosphere, if they can get in in the first place they why can't they get out..??? We understand the greenhouse gases preventing the heat from escaping but why would they stop the heat from getting in in the first place. If someone can give us a clear answer I would appreciate it.

 

thanks for you time.

 

Mandy

 

 

Mandy, the answer lies in the way different wave lengths of light are absorbed. The air is more or less clear to visible wave lengths but not to longer wave lengths that are emitted after visible light is absorbed by the solid earth...

[MJKeulen]

That does make sense, I'll tell him tonight, thank you very much.

[iNow]

Expanding on Moontanman's point... The light enters in the form of visible light. When light has a wavelength in the visible range of the spectrum, it's generally unaffected by the atmosphere. That's why not much happens on its way in.

 

However, that light then hits the ozone layer and experiences some turbulence and begins to change form (mostly the ultraviolet and more energetic types of light are filtered out).

 

That light continues toward the earth and it later hits the ground and gets absorbed, heating whatever it hits, and then those objects being heated (like the ground) re-radiate that light back outward in a different form... a form known as infrared. The heated ground radiates light in a different form back out toward space. It's still light, but it's a different wavelength on a different part of the spectrum.

 

It's the infrared wavelengths of light that get absorbed by greenhouse gas molecules and why our average annual temperatures have been rising consistently since the start of the industrial revolution. The CO2 and methane and other similar molecules we keep pumping into the air act like a blanket trapping in the infrared radiation that is trying to escape back out into space.

 

Those molecules in the atmosphere just don't interact with the visible light coming in since it's in a different form... It has a different wavelength that doesn't react the same way as the infrared wavelengths do on the way out.

Edited August 14, 2013 by iNow

[MJKeulen]

That's even better... thanks so much

 

[iNow]

You should be proud that your son is asking such thoughtful and excellent questions already at the age of 7. You should be even prouder that you're the type of parent who loves him so much that you're willing to spend time educating yourself well enough to be able to offer accurate and well informed answers to them. Cheers.

[MJKeulen]

Thank you for your lovely comment. I am truly blessed to have my little boy, and I'm well aware of his intelligence and want to assist him in anyway I can so he can success. #feelinghappy