[Ihsaan]

I know the atmosphere at sea level is about 1 bar and at 10msw its 2 bar. Can anyone tell me what the pressure would be just below the surface of water? At 1cm would it be 1.001 or higher due to the density of water?

 

[Chris Lewis]

To all intents and purposes the pressure increase is linear.

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[Mike Ferguson]

er, didn't you just answer your own question? it would be approx 1.001bar due to the density of the water. the right answer is that it depends on the surface air pressure at that moment and the density of the water in question.

 

[Ihsaan]

er, didn't you just answer your own question? it would be approx 1.001bar due to the density of the water. the right answer is that it depends on the surface air pressure at that moment and the density of the water in question.

Thats what I thought, just wanted to check. I wasnt sure if the physical characteristics of water meant the transition from air to water meant the increase would be non-linear.

 

[Mike Ferguson]

in that case you need an answer from a physicist not an engineer, engineers will always say close enough not to matter when variables get small.

I would imagine it depends on how agitated the surface layer is, temperature of the surface layer compared to deeper layers, amount of suspended particulates, etc

 

[nigelH]

Water is very consistent. 10 meters of fresh water is 1 bar extra. 1 meter is 0.1 bar extra, 1cm is 0.001bar extra.
Water is very incompressible. At 5Km deep it compresses about 2% so you are not an extra 500bar there but about 505.

If you're taking about fractions of a bar near the surface then beware that the surface pressure depends on altitude and the weather before you even get wet.
HTH

 

[Ralf]

The pressure depends on depth and water density. The denser the water is the heavier it is and the more pressure.

This explains the small difference between sea water and fresh water and also warm water and freezing water.
If the surface water is hot and the bottom is cold, then the pressure increase is not linear.
This is a theoretical situation more than a practical one.