Why is it colder at higher altitudes?

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Offline thedoc

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Why is it colder at higher altitudes?
« on: 09/04/2013 10:30:01 »
Riaz Mahomed  asked the Naked Scientists:
They say that air cannot absorb visible radiation but the Earth can, releasing it in the infrared form and enabling air then to absorb it and get warm, thus allowing for the process of convection to take place, right?

If this is the case, then why is mount Everest covered in ice?  After all that is also a piece of Earth isn't it?I know that the air is colder at that altitude but the mount (which is supposed to be able to absorb visible radiation), at day time, is constantly bombarded with sunlight.  Can't we reason that in the vicinity of the mount should be very cold but in the actual mount very hot?

Isn't what it happens in the moon where in the sunlight is close to 100oC and on the shade is close to -150oC and yet there is no air to raise daylight temperature?

So if the moon doesn't need atmosphere to be hot in daytime why does the earth need it.

What about the human body, can it absorb visible radiation?  If yes then can't the same reasoning done to mount Everest be applied to the human body?

I look forward to hearing from you.  Sorry about the long email.  Thank you very much.  Bye.

What do you think?
« Last Edit: 09/04/2013 10:30:01 by _system »


Offline yor_on

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Re: Why is it colder at higher altitudes?
« Reply #1 on: 09/04/2013 11:28:09 »
two things, both having to do with atmosphere. Less pressure means fewer atoms/molecules taking up a same amount of space. They can't 'bounce' as much as molecules under higher pressure. Think of water boiling in a pressure cooker. When they 'bounce' their kinetic energy get released as IR (radiation) amongst other things warming us. Then you have 'energy states' by them self to consider. So the further down, meaning closer to earths surface, the higher the air pressure, meaning that the atoms further down should have more energy in their 'natural state'  to waste as radiation (IR). And then you have winds of course, lowering the temperature by transporting away heat.
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