Wind Chill

If the outside temperature is, say 35 degrees, and a truck with a hose full of water, like say, a firetruck, drives down the highway at 60 miles per hour, will the resulting wind chill actually freeze the water in the hose, or is wind chill just a “feel”?

The wind chill, explained simply, means that you lose heat (and thus feel as cold) as if it were the lower temperature. However, you (barring some minor fluid dynamics effects) will not cool below the actual ambient temperature. Thus, the water in your example will cool to 35 degrees much faster than standing still, but will not cool below 35 degrees (once again, barring some fluid dynamics effects, which could make it slightly warmer or colder, but generally you can ignore those from a layman’s standpoint).

Wind chill is basically a physiological response. It reflects the rate at which heat is drained away from exposed skin.

There is a related phenomenon that occurs with moving air and temperature. A moving mass of air will cool a body down to the ambient temperature faster than a still mass will. But this does not mean that it will cool it [below the ambient temperature.

So wind chill is a human sort of thing, and not any strict temperature in the real world.

OK. Maybe weasels feel wind chil…

Yep, wind chill is just an increase in the rate of heat transfer from the body to the surrounding air due to breakdown of boundary layers at the skin surface and forced convection.

So the hose wont freeze.

It will get cold faster, though. I ride my motorcycle to & from work in (occasionally) sub-zero weather. When my eyes tear up behind the goggles, it takes very little time for that stuff to freeze to the lens; much less than it would take without the wind.