sensation of cold and hot

[devayaani]

When I try to dip my bare arm in a tub filled with water at 17 degree Celsius, I immediately shiver (my arm at least). However, when I am walking in the street when the air temperature is even less than that of the tub water (i.e. less than 17 degree Celsius), my bare arm will not shiver.
Why the arm skin perceives so differently when dipped in water and when in air?
Thank you for the explanation.

[devayaani]

Thanks EDDIE51

[fo3nix]

Just to add, it's also why for example, metal door knobs feel cold to the touch, where as the wooden door itself doesn't. Metal is a much better conductor of heat than wood, so the heat from yourself is transferred that much faster upon touch.

[Ice.Maiden]

Also, when you're outdoors in the cold, the hairs on your arms stand up to trap the air and try to keep the heat around you. When you submerge your arm in cold water, the hairs are flattened against the skin, so therefore don't have much input in what nature put them there for.

[fo3nix]

tonyted: to my knowledge, because the gap still allows convection to occur, which is a transfer of heat in fluids and gases.

The stuff they are filling cavity walls with now is a very good insulator still, and traps air in little pockets so that convection doesn't really happen.

[rov1200]

Its possible to dip your hand in near to boiling water if you first immerse it in cold water. Why the brain is fooled in this way is a mystery.