Water well below freezing point.

[AeroEngy]

Originally posted by: dkozloski
... Where the river is slower moving it freezes over to ice thicknesses of as much as five or six feet.

Just thought I would comment on another disturbing scene (... at least for me) while I was in Alaska. There was a snowplow removing snow on a road that just happened to cross a frozen lake (Quartz Lake maybe?). I know this is probably common practice in regions were there is a sustained <0°C temp and large ice thickness occur. However, it still freaked me out to actually drive on it especially after seeing the river and many various streams flowing freely.

 

[Paperdoc]

Ice roads are common in cold areas. The builders are SUPPOSED to build and use them only after checking that the ice thickness is adequate. And, of course, then someone has to monitor the ice as the season warms up again! These things are ONLY done in water with very slow flow so that currents of slightly warmer water don't cut away the ice from underneath. And the trucking operators have several back-up plans for when the ice fails, anyway.

In many areas of Northern Ontario there are small isolated communities with no roads and no good way to bring in large quantities of supplies. Air transport is VERY expensive. So they arrange that, during the winter, they "build roads" across the ice of local lakes and through the bush between them, then use large trucks to haul in a year's supply of certain goods. I can recall news stories from a few years when the winter was not cold enough for long enough, and the system didn't work. There was a real panic figuring out how to pay for the expensive ways to transport the necessary goods that did not make it by truck on ice roads. I am sure the same thing happens in many northern areas.

I'm in northern Minnesota. Around here there are several ice roads built by local residents for recreational uses. People drive out for ice fishing or whatever, or maybe just as a short cut across a lake to where they're going, or go out on snowmobiles for a good run, once the ice is solid enough.

 

[spidey07]

It has to be from the movement of the water.

At the wine store they have a "wine chiller" tub. It's a special tub of very cold water (15 degress) that is moving and circulating. It doesn't freeze. But it sure will cool a bottle of wine...something like 7 minutes.

 

[jagec]

Originally posted by: Paperdoc It also is not frictional heating from turbulent flow. That does not happen. If it did, water downstream from rapids would always be hotter than upstream, and you are talking HUGE temp difference.

Mmm, that's not entirely true. Water certainly does heat up from friction...where else does the energy go? Hydroelectric dams would not work if they could not divert some potential energy to electrical, rather than thermal energy. However, this effect is rarely noticed because of the high specific heat of water and the ready transfer to the surrounding environment.

 

[Matthias99]

Originally posted by: OSX
This is also assuming that wind chill affects water, which IIRC, it doesn't.

Just wanted to comment on this -- 'wind chill' will make water lose thermal energy to the air faster (roughly as if it was exposed to non-moving air at the 'wind chill' temperature, though this can vary wildly with exposed surface area, etc.) That's actually how the 'wind chill' calculations were originally derived (or so I've read) -- they measured how fast the temperature of a fixed volume of water changed when exposed to various combinations of temperature/wind.

However, it does not change the actual freezing point of the water. You could have hurricane-force winds with the air temperature at 1 degree Celcius (and a 'wind chill' way below the freezing point) and water exposed to it would never freeze. It would just cool very rapidly to ~1 degree C and stay there.

As far as the OP, I'm with the people saying a combination of turbulence and heat/warmer water coming from below ground.

 

[Whoozyerdaddy]

Originally posted by: AeroEngy

Originally posted by: dkozloski
... Where the river is slower moving it freezes over to ice thicknesses of as much as five or six feet.

Just thought I would comment on another disturbing scene (... at least for me) while I was in Alaska. There was a snowplow removing snow on a road that just happened to cross a frozen lake (Quartz Lake maybe?). I know this is probably common practice in regions were there is a sustained <0°C temp and large ice thickness occur. However, it still freaked me out to actually drive on it especially after seeing the river and many various streams flowing freely.

Still water freezes faster than running water. I don't know why. IIRC it only takes 4" of ice to support the weight of a car. The lakes up here can freeze to a depth of several feet depending on the size of the lake. Ice roads are all over. People drive the Chena River from bar to bar all winter long and there is a seasonal ice bridge that people use as a short cut from University West to the Airport.

 

[dkozloski]

Originally posted by: Whoozyerdaddy

Originally posted by: AeroEngy

Originally posted by: dkozloski
... Where the river is slower moving it freezes over to ice thicknesses of as much as five or six feet.

Just thought I would comment on another disturbing scene (... at least for me) while I was in Alaska. There was a snowplow removing snow on a road that just happened to cross a frozen lake (Quartz Lake maybe?). I know this is probably common practice in regions were there is a sustained <0°C temp and large ice thickness occur. However, it still freaked me out to actually drive on it especially after seeing the river and many various streams flowing freely.

Still water freezes faster than running water. I don't know why. IIRC it only takes 4" of ice to support the weight of a car. The lakes up here can freeze to a depth of several feet depending on the size of the lake. Ice roads are all over. People drive the Chena River from bar to bar all winter long and there is a seasonal ice bridge that people use as a short cut from University West to the Airport.

Somebody went through the ice by Pike's Landing with their new pickup before Christmas. The ice is not as thick as usual.

 

[RaynorWolfcastle]

I live in Canada and there's a portion of the river behind my house that never freezes, regardless of how cold it gets. I'm fairly certain that this is related to the movement, as the areas near the banks of the river will freeze but the turbulent areas will not. Also, the river will freeze (at the surface) downstream where there is less turbulence.

I'm not a chemist or a physicist but I would assume that it has something to do with the movement preventing the water to form the bonds necessary to have a crystalline ice structure.

 

[Cogman]

Something that I'm not exactly sure of. I was talking to a friend once and he said that it was possible to take water well below freezing, but the conditions where that the water had to be pure and the in a smooth container in a dust free enviroment. He said that there was some experiment that he watched (he was german so it would be in german) where the water temp. was dropped below zero then the scientist dropped a hair into the water, which froze it instantly.

I know that water can be raised above its boiling point, and it does not have to be too pure. I have before, myself, raised it to such a point in the microwave. And then I put some instant drink mix into the water and it exploded and started boiling very rapidly.

Anyways I post this mostly to see if this can be confirmed.

 

[imported_Tick]

Originally posted by: Cogman
Something that I'm not exactly sure of. I was talking to a friend once and he said that it was possible to take water well below freezing, but the conditions where that the water had to be pure and the in a smooth container in a dust free enviroment. He said that there was some experiment that he watched (he was german so it would be in german) where the water temp. was dropped below zero then the scientist dropped a hair into the water, which froze it instantly.

I know that water can be raised above its boiling point, and it does not have to be too pure. I have before, myself, raised it to such a point in the microwave. And then I put some instant drink mix into the water and it exploded and started boiling very rapidly.

Anyways I post this mostly to see if this can be confirmed.

Yeah. Under certain conditions, thier can be a lack of nucleations sights for ice crystals and/or water vapor bubbles. Under the conditions you described, this can happen. Then, when you introduce an irregularity into the inviroment, the phase change can begin. This is because the water can stick to the irregularity, holding it stationary, increasing the number of energy-favorable phase-changeing collisions.

 

[TheYak]

Apart from the statements concerning friction, earth temperature, pressure temperature, et cetera, perhaps it will help understanding if you look at the problem a different way. Don't think of ice as being cold, but merely the solid state of a liquid. All solids are that way because there's little-to-no molecular motion. The less movement, the stronger the bonds (and vice versa). When there's more energy being introduced to a system (such as running water), the immobile state could only be reached if the temperature was cold enough to allow the additional energy to be nullified. Water's liquidity is due to having very loose atomic bonds, which is why it's also considered the "universal solvent". Simply put, the energy introduced to the system exceeds the strength of the atomic bonds - it doesn't necessarily have to be converted to heat energy.

Hope I didn't come off condescendingly, just thinking aloud trying for a different approach to the problem.

 

[AeroEngy]

Originally posted by: TheYak
Apart from the statements concerning friction, earth temperature, pressure temperature, et cetera, perhaps it will help understanding if you look at the problem a different way. Don't think of ice as being cold, but merely the solid state of a liquid. All solids are that way because there's little-to-no molecular motion. The less movement, the stronger the bonds (and vice versa). When there's more energy being introduced to a system (such as running water), the immobile state could only be reached if the temperature was cold enough to allow the additional energy to be nullified. Water's liquidity is due to having very loose atomic bonds, which is why it's also considered the "universal solvent". Simply put, the energy introduced to the system exceeds the strength of the atomic bonds - it doesn't necessarily have to be converted to heat energy.

Hope I didn't come off condescendingly, just thinking aloud trying for a different approach to the problem.

That does make a lot of sense. However, I still wonder what the temperature of the flowing water actually is. If I had to guess it is 32°F sense temperature is really just the average molecular kinetic energy. So if the temp was any lower then the molecular motion would be slower and it would not be flowing.

Well I just found this morning that I have to be back in Alaska in the next couple days so maybe I will test it out ... and hopefully not fall in.

To: dkozloski
I hear that I should go to the Pump house in Fairbanks. Any recommendations.

 

[TheYak]

Aside from anecdotal and contemplative evidence, I haven't found anything worthwhile during casual searching concerning this question. One interesting thing to note, though, is that I found out that the pressure mention had it backwards (the pondering as to whether greater pressures towards the bottom might be adding energy or heat into the mix). Water freezes at higher temperatures while under pressure.

 

[StopSign]

Did you know that you can boil water with only ~75 C at the top of Mt. Everest?

 

[cougar1]

TheYak - Actually, you are the one who has it backwards. Water freezes/melts at lower temperatures while under pressure. This is one reason why ice skating works, since the pressure under the skate causes a small amount of the ice to melt, creating a very slick surface.

Note that water is the only material for which this is the case. Most other materials do freeze at higher temperatures while under pressure, but water is the exception. This is related to the fact that ice is less dense than water and is the reason why ice floats, while most solids will sink in their melt.

 

[TheYak]

I was thinking bass-ackwards there. Under pressure, water will not freeze or will thaw at the same temperature. You're right. However, pressure still doesn't come into play due to the creation of heat. It has to do with the hydrogen bonds being stronger than the bonds found in most liquids rather than temperatures generated by friction or pressure changes.

While there might be temperature variation due to this pressure, the temperature is still not the contributing factor. Also, the pressure wouldn't be due to the flow of the stream as much as the ~1ATM + Lb/Foot^3 amount of pressure. You see the same freezing phenomenon in a lake with the surface freezing solidly, with the water just below the ice surface holding at a steady 32 degrees F.

 

[dkozloski]

Water does freeze normally in Fairbanks. http://newsminer.com/2007/01/22/4663/

 

[Aeridyne]

 

[Aeridyne]

if the water is still flowing and moving, maybe it is harder to make it freeze...

 

[Zoomer]

At 1 atm,
Specific heat capacity of pure water: 4200 J per kg per deg C
Specific heat of fushion of pure water: 4200J per kg

You can take 1kg of water as 1 litre.

 

[Paperdoc]

My old CRC Handbook of Chemistry and Physics says for pure air-free water at 1 atm absolute pressure and 0C temperature, the Heat Capacity is 4217.7 J per kg per degree Celsius, and the Heat of Fusion is 79.72 cal per gram, or 333,548 J per kg (if we use 1 cal = 4.184 J to define the calorie). So, to cool a kg of water from 1C to 0C you have to remove 4218 J of heat energy. But then to convert it to a kg of solid ice still at 0C, you have to remove a further 333,550 J of heat energy!! That's almost 80 times as much!! This is why flowing water seems never to freeze. The rate of heat removal from the cold water is slow enough that the water you are watching does not loose heat fast enough to freeze before it is gone from view.

Sure, there IS frozen ice near the edge of the stream (or hole in the ice). At its surface is a dynamic equilibrium. For every gram of liquid water that freezes to add to the ice block, enough heat has been removed from it to melt another gram of ice back into water. The only way for there to be a net increase in the ice mass that we happen to be watching is for all that heat to be removed from the water entirely, say by currents of air below 0C flowing over it. And in fact, in a sustained cold period the open water area slowly gets smaller as more ice builds up around the edges. But if there's any other heat source (say, sunshine with its infrared components), the input of heat may outweigh the removal by moving air, and the ice edge melts back a bit. The whole thing is a constantly-changing equilibrium disturbed by short-term external influences (air and sunshine being external to the water / ice system).

 

[Agent11]

Alaska is a pretty volcanically active place.. Could be factoring into things. What location in Alaska are we talking about?

 

[dkozloski]

The Tanana River drainage in the interior has no active volcanoes.

 

[pradeep1]

If the water is emerging from an artesian well or some other underground source, then it would be closer to the constant temperature of the earth below the frost line, which is like 65 deg. F. This means that it is possible the water was significantly warmer than the surrounding air, and with the added minerals dissolved in it, it could still be flowing when it was -60 F outside.

As a side thought, consider this, in the Artic the water doesn't freeze in the ocean even though it is extremely cold all year round. You may have ice shelves/sheets, but the entire thickness does not freeze.

 

[imported_iNGEN]

PaperDoc's comments seem accurate to me.
However, there is a larger cause. If you pull a USGS topographical map of the area you will find the Tanana river is a gaining river (I actually found that info on a Park Service website). What that means is that the groundwater level exceeds the static recess of the river. So the water you see in the river is actually only a portion of the total water flowing with the river. I dunno what the alluvial soil depth is, but I'd guess it is at least three times as deep as the river. If my presumption is true then you actually only see somewhere between 1/2 and 1/4 of the total water mass. With the greater portion of contact area in a much better insulated environment, the ground. As water continually cycles between ground and river, the water receives heat from not only friction and the sun that hits the river, but sun at strikes all of the ground where connected groundwater moves.

In short, there is WAY more thermal mass than what you see. That mass has a greater source of heat than what you see.