frozen water?
 

i was watching nova last night and these crazy french men decided to climb this glacier to discover if there were hidden wells of water in them. during their dive into this glacier they noted that the water temperature was below freezing. i always thought that when the temperature gets below 32 degrees water turns to ice. does anyone know why this didn't happen?

One possible explaintion would be the presence of some chemical substances( such as chlorides) that would lower the freezing point.

Water freezes at 32F at one standard atmosphere. Increase the pressure and the freezing point goes down. Water at the bottom of the ocean can be significantly colder than 32.

Interestingly, there is a point along the temp/pressure scale where all three forms can exist simultaneously: solid ice, liquid water and water vapor (steam).

You're right about the pressure.

And as an aside, water at the surface of the ocean can be below 32 and not be frozen as well. The freezing point of salt water is dependent upon the amount of salt in solution. If the water was to hold as much salt as possible (you put more salt in and the salt remains crystaline) the freezing point is somewhere below zero.

Also, I doubt that this is applicable in this situation, but nonetheless.

Water can be liquid at 32F, there is a 'grace' period where water goes from a liquid to a solid that requires energy. The 32F water is still liquid and the molecules begin to line up in a crystilline form. If you were to contine to remove energy from this water at a FAST rate, while the molecules are still lining up to crystalize you can super-cool the water well below 32F. Though, the crystallization will catch up and it will freeze solid.

on a side note: google for Super Cooled Water, interesting stuff.

-SF

Ever put water in a ice try and notice it hasn't frozen, then you move it and it freezes instantly? Had it happen once or twice.

Neat!

thanks a lot for all your answers. no doub this is one of the best places to find out things.

Moving water seldom freezes, as well. Large bodies of water are usually in motion, currents and such. The faster its moving, the lower the temp at which it freezes. Something to do with Thermodynamics. :)

The water doesn't have the opportunity to form ice nuclei, all of the water molecules have to line up in a specfic way before they can crystalize.

It's neat stuff.

BTW, if you're bored and want to learn about the many strange properties of water click here.

http://www.lsbu.ac.uk/water/strange.html

;)

-SF

Thats an interesting website. Makes me wish I paid more attention in science ;)

Mostly true, but moving water does freeze on quite a few occasions. There are people who actually climb frozen waterfalls.

not really true--look inside a slurpee machine. the slurpee machine probably operates at slightly below 0 degrees celsius, to make up for the mechanical energy added to the system and for the fact that sugar water has a lower freezing point, but my guess is that it's not that much colder.

large bodies of water on this planet are usually salt water and therefore have lower freezing points. large bodies of water on this planet that are freshwater, such as lake michigan, will freeze later in the season than a small pond, but that's because the heat capacity of water is very high and it takes more days of below freezing temperatures before ice can form. and once a layer of ice forms on top, it insulates the water below, which can stay above freezing for a much longer time.

Slurpee machines are a good example of a frozen mass of ice crystals that are 'lubricated' by the sugars and other additions. The Slurpee solution is constantly agitated and the liquid beings to form ice nuclei, because of the constant agitation there is little condensed crystal growth. There are just a lot of little crystals, the sugar never really 'freezes' it tends to hang around and help to keep the crystal size small.

I'd be interested in seeing how 'cold' Slurpee can get with constant agitation... Most likely VERY cold.

-SF

alright, you made me go out and do some research...

slurpee machines operate at -15C (5 degrees F). learn something new every day...

This is interesting...

Consequently, pure water can be cooled well below zero (sometimes to -40°C) before ice forms.

http://www.phys.unsw.edu.au/~jw/unfreezable.html

-SF

I'm relating a story my Dad told from when he was at Cornell, circa 1942, of a professor who owned an automobile and asked the folks at the local shop to put "water that doesn't freeze" in the radiator. Lake Cayuga never froze, and that was the new content of his radiator. As they would say on Fark: Upset ensued.