Dave B wrote:Wind chill won't cause the tube to freeze any faster unless the outside is (continuously) wet (i.e. latent heat loss from evaporation). Although, wind may cause what little body heat is radiated to the tube by air contact to be convected away (but is probably a negligible amount anyways).
I don't want to argue with science, but I don't think that's true. Convection will increase the rate of temperature change of the tube.
What I assume you mean is, the "wind chill" temperature value is meaningless. If it's 33 degrees outside with a wind chill of -10, the water is not going to freeze.