Frozen water bottle temps

I carry a thermometer with me : )

If it’s maybe 28F my water will bottle will be partially frozen in the morning, slushy water

Maybe 25F and it will be mostly frozen but still enough water which I can heat up in my pot the next morning, then pour back into bottle to melt it.

Maybe 20F will be totally frozen.  Better bury the bottle somewhere under some insulation so there will be a little water in it.

Or, pour some water in your pot the previous night.  It’ll freeze, but you can heat it back up on stove…

another thing is the cap.  If you screw it on tightly it’s difficult to unscrew when it freezes.

if you barely have it screwed on – better.

“How frozen” it gets of course depends on how much water is in it–little water, mostly ice; lotsa water, more slushy.  But it doesn’t have to get below 32 to get at least some slush.  If the bottle is visible to a clear night sky, it can freeze even well above that.  I’ve seen water on the ground iced over when it didn’t get below 40 the night before.

Regarding frozen caps, I always turn the bottle upside down if I expect the possibility of light freezing.

Interesting to see different data points above. I would hypothesize that ground temp is a factor too (and shelter design, site selection, dewpoint maybe, etc…

If the bottle is visible to a clear night sky, it can freeze even well above that.

Oh wait you are talking about radiative cooling I think. That is interesting. Thank you. Some of those times I was clear to the night sky and very surprised the bottles were half slush.

Oh wait you are talking about radiative cooling I think.

Yep, it’s the important driver people tend to ignore.  It’s a bigger driver of fly condensation IME, but can speed up water freezing too.

As you may know, the ancient Persians and Egyptians made ice via radiative cooling at night and stored it in insulated structures during the day.

On the internet, it is often claimed that ice was produced via rapid evaporation, but that is one of those often-repeated internet fallacies, evaporative cooling cannot reduce the temperature below the wet-bulb temperature. Evaporation could help with the cooling process, of course. Even AI will give you a confusing answer unless you really ask the question in a precise way.

Probably not relevant to the conversation at hand, but something I’ve always found fascinating.

Yeah, I find it fascinating that they used evaporative cooling for a refrigerator – a ceramic pot soaked in water below ground or whatever.

I’ve tried cooling a plastic bottle with a covering that I get wet, then evaporative cooling makes it colder.  I need to investigate that further – different coverings and how many degrees colder does it get, how long does it take.  Might be useful when it’s hot,  get the water a little cooler.

You old timers may remember the canvas water coolers used on cars.

https://www.marquettehistory.org/blog/canvas-water-bags

hang on hood ornament?  then it would be in the sun, hmmm…..

12 degrees cooler – that would be a big improvement

To put things into perspective, cooling 1 g of water by 1 degree C requires 4.184 Joules

To freeze 1 g of 0 C water to ice requires 334 Joules or almost 80X the energy

To put things into perspective, cooling 1 g of water by 1 degree C releases 4.184 Joules

To freeze 1 g of 0 C water to ice releases 334 Joules or almost 80X the energy

FIFY.  😉

[Your point is very well taken.]

My own rule of thumb: it takes as much energy to melt snow/ice to water as it does to bring that water to the boil.
So I always try to find liquid water near where we camp, especially in the snow.

Cheers

Roger,

Excellent rule of thumb (that is what I do), and the fundmental math still works.

Energy to melt 1g  of ice – 334 J

Energy to heat water – 1 g of water form 0-100c – 418.4 J

Rarely is water at 0 C so the approximation is perfect.  My 2 cents.

Mid 20’s is when my shoulder strap mounted 1L smart water bottle starts to slush while hiking.

My problem is it freezes over night.

Sometimes I can surround it with insulation and it will still be liquid in the morning.

Or, if I have a fire, I’ll set water bottle next to fire and warm it a little, like 50F

put it in the bottom of your quilt/bag, it wont freeze.  That and you will use less fuel.  My 2 cents.

What Jon said.
Cheers