# Water vs. Air : Heat Absorption/Capacity

I am not a physicist by any means and not even a current student, but nonetheless I am looking for an answer. Here is what I have gotten so far from university websites and other various resources on the internet (Wikipedia's Heat Capacity page lacks citations for this):

Water's specific heat capacity is 4200 Jkg-1K-1 and Air's is 993 Jkg-1K-1 therefore water has 4.23 times more specific heat capacity.

Water has a density of 1000/m3 and air has a density of 1.275/m3 therefore water would be 784.31 x denser than air.

So would that mean that the amount of times more volumetric heat capacity water has compared to air would be 784.31 x 4.23 = 3317.63? Are my numbers even right?

Thanks in advance.

## 1 Answer

Your numbers are (approximately) right (there is no use to be so precise, about air density for example, since it varies with temperature etc.), and your thought is right, too.

The difference is very big, as you see. You have to consider though, that this is valid for dry air. In practise, if you have some air streaming upwards in atmosphere, it might reach a point where it gets so cold, that the contained water vapour begins to condense. This sets free some energy which slows down the cooling, so in this case the heat capacity of air is bigger, by some factor 2-3.

## protected by Community♦Jul 3 '18 at 21:08

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