It was 20 in the shade yesterday - nice and warm. So why does the swimming pool feel cold at 25 or even higher?
Dave - The thing is that the temperature you feel isnít the temperature of the air or the temperature of the water, itís the temperature of your skin. If your hand is sitting in air, your body is always producing heat quite rapidly, and air is a very bad conductor of heat, so it doesnít take the heat away very fast. So even though the air might be 20 degrees centigrade, your skin might still be still be somewhere at 30 perfectly happily. Water is a much better conductor of heat, very high heat capacity, so if you put your hand in even something at 28 degrees centigrade, the surface skin is going to very rapidly get almost to exactly the same temperature as the water, so that will feel colder even though the water is warmer than the air was.
When you "feel cold" it is a relative sensation, i.e. it tells you not what temperature you are, but whether you are loosing heat.
@Neil_J_Thomson asked the Naked Scientists: It was 20 in the shade yesterday - nice and warm. So why does the swimming pool feel cold at 25 or even higher? Neil (Kent) What do you think? @Neil_J_Thomson, Tue, 7th Jun 2011