Assume you are stranded on a frozen body of water, by yourself, waiting for help to come. In order to simplify the problem, let’s also assume you have no clothing (maybe just your underwear, for those of you who are shy).
Where would you rather wait? Out in the open where the temperature with wind chill factor feels like -5 degrees F (-20 C), or in the still water at about 32 degrees F (0 C)? In other words, which is going to remove your body-heat faster? How can we go about figuring this out?
Further, can we estimate the wind-chill temperature at which you would be safer jumping into the water while you wait for help?
Is it all irrelevant? Are you going to die within 5 minutes anyway?
Jumping into cold water = fast death. That’s true even in much warmer water than you state. This is pretty much drilled into your head when you grow up someplace cold and surrounded by lakes.
I don’t have any cites for you, but an easy Google search on “cold water survival” brings up dozens of pages.
Let me amend that to, “fast painful death”. Er, not that standing naked on ice in -5 windchill is exactly un-painful, that is.
It all has to do with the rate at which heat is being pulled away from your body.
Water conducts heat much more rapidly than still air. To maintain a steady-state body temperature in water, you have to use much more energy than you do in still air to continuously replace the heat that leaves your body.
Wind increases the rate at which heat leaves your body by continuously pulling away the layer of warm air next to your skin and replacing it with cold air. You keep trying to warm up a new air layer all the time, resulting in much greater energy use in windy conditions than in still air.
This is why wet windy weather a couple of degrees above freezing is far more uncomfortable to the skin than dry still weather at -10C. (Windy weather at -10C starts to become uncomfortable again…)
I was in a hurry when I first posted, but I wanted to add - even when it’s warm out, cold water is dangerous. I kayak on Lake Superior, and I will never go out without a wet suit and PFD. Sucks on a 90 degree day - wet suits and PFDs are HOT - but I know that if I go over in Lake Superior, even in August, I have maybe 30 minutes before things start to go south.
Here’s an interesting link. The chart at the bottom claims 15-30 minutes before unconsciousness in 32.5 degree water, and 30-90 minutes survival time.