eli5: Why is 70 degree F water so much colder than 70 degree F air?

Question

I can hang out buck naked in 70 degree F outside all day but not touching 70 degree F water.

In: Earth Science

Answer 1

It’s because of the efficiency of heat transfer–when thermal energy moves from something warm to something cooler. In this case, from your 98.7 degree (F) body to the 70 degree air or water. Water is a better conductor than air, so when you get into the water heat escapes/is transferred out of your body at a much faster rate, leaving you feeling colder, faster than you would if you were just standing in 70 degree air.