I CBB explaining it but wiki can:
http://wiki.answers.com/Q/Why_does_ice_ ... han_in_air
This paragraph is also interesting if your just dying for a cold one and realise you forgot to put the stubbies in the Ice box
By the way, ice water will also chill things faster than very cold air. If you submerge a test tube of room-temperature water in an ice bath, it will coll down much more rapidly than if you had placed the test tube in the freezer, even though the freezer is colder than the ice bath. Again, this has to do with the higher heat capacity of water than air.