3 ms·

Thank you for doing the math! At least in my area in central Europe, 10°C would be wildly optimistic in summer. I also presume when submerged in cold water, yo

Thank you for doing the math! At least in my area in central Europe, 10°C would be wildly optimistic in summer. I also presume when submerged in cold water, your body will start heating up, at first. So there is probably only a narrow temperature window for effective cooling. Not to mention, you may have to work and be awake to exchange the water, and being constantly wet for a prolonged time may come with it's own set of health problems. I imagine there could be a situation with a deadly wet-bulb temperature, but below body temperature, where a large body of water may work to cool the body by convection, no?

jameshart 3y ago
A large body of cool water works great at moving heat way from you, obviously - an ‘acre foot’ of water is 1.2 million liters - 300,000 gallons. So a fairly small one acre lake that’s ten feet deep has 12 million kg of water, which can absorb 48GJ of heat before it rises in temperature by a single degree. The big question though is how long will that lake remain cooler than the air in the face of wet bulb temperatures around body temperature. Thermal equilibrium will win in the end.
- jijijijij 3y ago
  Yeah, but the question rather is, would let's say 32°C water, 5°C temperature gradient, work to cool the body, if completely submerged? When ambient conditions are deadly wet-bulb 32°C, would it still cool the water to its original 32°C? So, my thinking would be, if the heat transfer from the body to the water and from water to air (through large surface) is sufficient. In a shaded pool, so all heat transfer from the outside is by convection and conduction. I guess, if it would be sufficient cooling, you could also "just" drink the water and remove hot sweat from the skin, or dispose urine, instead. In theory, never mind electrolytes.

3 ms·

Thank you for doing the math! At least in my area in central Europe, 10°C would be wildly optimistic in summer. I also presume when submerged in cold water, yo

by jijijijij 3y ago

jameshart 3y ago
A large body of cool water works great at moving heat way from you, obviously - an ‘acre foot’ of water is 1.2 million liters - 300,000 gallons. So a fairly small one acre lake that’s ten feet deep has 12 million kg of water, which can absorb 48GJ of heat before it rises in temperature by a single degree. The big question though is how long will that lake remain cooler than the air in the face of wet bulb temperatures around body temperature. Thermal equilibrium will win in the end.
- jijijijij 3y ago
  Yeah, but the question rather is, would let's say 32°C water, 5°C temperature gradient, work to cool the body, if completely submerged? When ambient conditions are deadly wet-bulb 32°C, would it still cool the water to its original 32°C? So, my thinking would be, if the heat transfer from the body to the water and from water to air (through large surface) is sufficient. In a shaded pool, so all heat transfer from the outside is by convection and conduction. I guess, if it would be sufficient cooling, you could also "just" drink the water and remove hot sweat from the skin, or dispose urine, instead. In theory, never mind electrolytes.