Naked Science Forum

General Science => General Science => Topic started by: arumalpra on 13/01/2013 07:30:40

Title: Can we cool the Earth's surface by pumping cold air down from the sky?
Post by: arumalpra on 13/01/2013 07:30:40
Just another crazy thought came to mind..

Remember cold sunny day? also warm sunny day?
Lets change atmosphere around us warm to cold .

With altitude temperature decrease at the rate of 6.4°C/km. Imagine there is mechanism to pump this cold air to the surface of the earth. we get cold sunny beautiful day.

And another thought pumping air from a desert to cold country?
Title: Re: cool the earth by pumping air from the sky
Post by: evan_au on 13/01/2013 08:09:31
To pump rarified air from high altitude down to sea level, you have to compress it. Compressing air makes it hotter.
Title: Re: cool the earth by pumping air from the sky
Post by: CliffordK on 13/01/2013 22:05:32
Quote from: evan_au on 13/01/2013 08:09:31
To pump rarified air from high altitude down to sea level, you have to compress it. Compressing air makes it hotter.
That is true if you are compressing it at sea level.  If you compress it at altitude, then bring it down, you could make cold air.

Essentially the water cycle naturally does this.

Water evaporates into water vapor, based on the temperature and vapor pressure of the water.

H2O then exists as individual molecules with a molecular weight of 18.  N2 has a molecular weight of 28, and O2 MW of 32. 

Thus, the "high energy" water molecules have a lower density than air, and rise.

As they rise, the atmosphere gets cooler.  When water condenses in the upper atmosphere, it releases energy in the upper atmosphere, and then brings the "cold" water back down to the surface.

Evaporation, of course, also removes energy from the body of water.
Title: Re: cool the earth by pumping air from the sky
Post by: Lab Rat on 13/03/2013 17:25:34
If you pumped air from a desert to a colder place, I'm assuming by some type of pipeline, the air would cool down as it got nearer to its destination.  This is due to the fact that hot air in cooler surroundings would try to reach equilibrium, and, in the time it would take the air to travel, it would probably cool down.