Don't greenhouse gases work in both directions?

Question

Don't they reflect heat from the sun as well as heat from the earth, and stop it from ever entering the earth and heating it up in the first place?

Answer 1

Big time = YES!

The ultimate 'greenhouse gas' is H2O!  In cloud form you can easily tell when it BLOCKS SUNLIGHT and HEAT - reflecting heat AWAY from earth.

The Science of Global Warming in Perspective

http://www.nov55.com/gbwm.html

A Fake Mechanism in the Stratosphere which Supposedly Creates Global Warming:

http://www.nov55.com/str.html

Watch Bob & Dana give the truth the Thumbs Down!!!

Edit:  (Quote Mike) - "Visible sunlight enters the atmosphere and travels all the way to the ground, you'd agree?"

Of course your joking!!  You have never seen clouds or been under them where they reflect more than one half the sun's emissions back into space?

You can witness satellite pictures of clouds which reflect light & heat back into space here:  (You can also see the thickness of the ultimate greenhouse gas)

http://weather.unisys.com/satellite/sat_...

Answer 2

No, because...

They're transparent to visible light from the Sun coming down, but not to infrared light (heat) coming up from the Earth.

Sunlight striking the Earth is reemitted at a lower wavelength.  The change is wavelength is what makes greenhouse gases work.

But hey, you could believe Rick's expert instead of thousands of Ph.D. climatologists.

"In graduate school, I studied yeast physiology and stumbled onto the basic control mechanisms for mushroom formation. But I was forced into seclusion by mental pain, so I moved onto the previously vacated family farm and did mushroom research."

Answer 3

Yes an no,roughly 31% is reflected back into space and 69% is absorb by the planet.Most absorption is in the oceans,so you can obviously see that energy does reach the planet.

Here's a good link, in simple to understand terms,showing reflectivity and absorption rates.

Answer 4

No, and anyone who says they do has a really bad understanding of basic science and how radiation works. And Roxi, as has been proven twice so far in answers to your question, you are going to have to get used to really poor and scientifically incorrect answers being spread by global warming sceptics.

I'll simplify it a bit: Visible sunlight (and UV too) enters the atmosphere and travels all the way to the ground, you'd agree?

This radiation warms up the surface of the earth. You allow sunlight to shine on something, it gets warm, right? This is reflected back towards space as infrared radiation (heat = infrared radiation, "far infrared" radiation to be precise).

Greenhouse gases have the property of absorbing and trapping infrared radiation (not the visible stuff which came in). In other words, they trap the radiated heat from the surface of the earth.

So what's so bad about this? Well, again to simplify things a fair bit: too little greenhouse gas is bad, and the planet will freeze. Too much greenhouse gas is bad, and the planet will boil. The proportion of greenhouse gases in the atmosphere is increasing quite quickly, and some of the more significant ones are produced in large quantities by us. This is where the debate begins.

Edit for Voice Of Reason (below):

yep OK, mea culpa, on whether the interaction of radiation with molecules is "physics" or "chemistry". So by "a number of" you actually mean "one", and a minor one that is completely irrelevant. Spoken like a true global warming sceptic.

On point 2, you beautifully support my first sentence - a lack of understanding of basic science and radiation! Infrared is L-O-N-G-E-R wavelength than visible, and this is very significant. Heat or thermal radiation is far-infrared, which is even longer still compared to visible light than "near" infrared. Hey, believe whatever you like - but you can't change the spectrum of electromagnetic radiation just to suit an argument against someone else. I've edited the terminology anyway to prevent you getting confused even further. Are we on the right wavelength? ;)

Answer 5

No, greenhouse gases are transparent to UV and visual wavelength light from the Sun.  The Earth re-radiates the radiation in the infrared (IR), and greenhouse gases absorb IR radiation.

This graphic explains it well:

http://en.wikipedia.org/wiki/Image:Atmos...

Answer 6

Mike,

While your answer is correct in its general direction you got a number of details wrong:

1) It's not chemistry involved here, it's physics.

2) Infared radiation is shorter wavelength radiation than visible light.