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yosemite 5.9
climber
santa cruz
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Topic Author's Original Post - Jan 3, 2012 - 11:09pm PT
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My recollection is that it takes three continuous nights at zero degrees for a quiet pond to freeze adequately for skating. This is based on old memories of many Nebraska winters, hunting ducks on farm ponds, playing hockey on cold nights on outdoor rinks and skating for miles one day on a frozen creek. Kids didn't sit on the couch in those days. This seems to be consistent with the temps of zero degrees for three nights in mid-December shown on Werner's graph that he contributed regarding the ice on Lake Tenaya in Toulumne Meadows in Yosemite. I wouldn't go so far as to call this a reliable guideline as there are other factors to consider. Like staying away from running water that thaws the ice and being sure the ice is supported underneath by water. Constant evaluation is important. Once the ice breaks up and then refreezes, it can be too rough to be fun. But three nights at zero degrees seems to be a starting point. Unfortunately, the weather seems to have warmed up in Yosemite and we may not have another chance to skate before it snows. If you want to watch for at least three nights of predicted zero temps, the following link might be helpful, though it seems to be based in Yosemite West which is farther west and at a slightly lower altitude. As of today, it doesn't look hopeful for the next week.
http://www.wunderground.com/US/CA/Tuolumne_Meadows.html
Anyone else got ideas that might help? I am only one person and other's experiences would add safety, especially for a large lake like Lake Tenaya.
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KabalaArch
Trad climber
Starlite, California
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Teneya Lake is still in condition as of 1/3/12.
I'd check with the Rangers before making the road trip, though. They've had a patrol on the Lake as of late.
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tooth
Trad climber
B.C.
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The depth of the lake and volume of water has more to do with it than 3 nights of cold etc.
We have a few lakes in our valley that are the same width, but one is much deeper and never freezes over - all that water has much more thermal capacity than the shallow lake.
Every single one will be different.
It could be -50 for a week and Lake Ontario may not freeze over, yet a pond will.
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nutjob
Gym climber
Berkeley, CA
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Q = m_water*c_water*(T_air - T_water)
And then you do some other stuff to figure out how long that rate of heat transfer will take to reduce the temperature of the water to 32
But you have to integrate because heat transfer rate slows down when the water temperature approaches that of the air
Hmm... I'm getting something wrong because not taking into account the heat capacity of the air, which is also related to humidity and temperature.
I should have just said "I don't know". Damn wasted college edumucation.
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Karen
Trad climber
So Cal urban sprawl Hell
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Was one of those people skating around on Tenaya Lake a few days ago, what an awesome experience.
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BooDawg
Social climber
Butterfly Town
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Even when the water temp gets to 32, it takes an additional loss 80 calories/gram of water (I think) to change its state from liquid to solid (ice). The ice will still be 'just' 32 degrees until/unless further heat loss occurs.
Is 32 degree ice any stronger or weaker than, say, zero degree ice, assuming they are equally thick?
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Mike Bolte
Trad climber
Planet Earth
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There is an interesting property of water which is its density increases with decreasing temperature to a maximum density around 39F. So, you cool the water at the surface of a lake and it sinks. This means you have to cool the entire volume of water in a lake to 39F before the surface water can be cooled down to 32F and freeze.
So, if you have two lakes with the same surface area, the deeper one (more precisely the one with more volume of water) is less likely to form ice.
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Allen Hill
Social climber
CO.
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The guy that makes our pond into a rink has some way of making it good to go by drilling a hole in the ice. There must be a thickness that is universally agreed on to be safe. Maybe a fishing forum based in North Dakota is a better place to ask the question!
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Mighty Hiker
climber
Vancouver, B.C.
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When is it cold enough to form ice on a lake?
Momentarily channelling someone else, when there's ice on the lake, it's cold enough.
Up here, we sometimes send what we call snowmobile poodles out to check the ice.
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HighTraverse
Trad climber
Bay Area
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News Flash:
Minnesota Congresswoman Michelle Bachmann fell through the Iowa ice last night.
And now back to your regularly scheduled programming.
From the Minnesota Dept Of Natural Resources
Wait to walk out on the ice until there are at least 4 inches of clear, solid ice. Thinner ice will support one person, but since ice thickness can vary considerably, especially at the beginning and end of the season, 4 inches will provide a margin of safety. Some factors that can change ice thickness include flocks of waterfowl and schools of fish. By congregating in a small area, fish can cause warmer water from the bottom towards the surface, weakening or in some cases opening large holes in the ice. http://icefishingtheoutdoors.com/safety.html
Asking when it's cold enough to form ice on a lake is like asking how long it will take Hell to freeze over.
You'll know when it happens.
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LongAgo
Trad climber
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Sometime in the 70's I think, I skated on Tenaya Lake with Tom Gerughty in a year somewhat like this one. All went well for a time, then Tom broke through into the very cold water. While he could just touch bottom being close to shore, it took some struggling and help to get out. Fools that we were, we had no change of clothes, so he stripped and wrapped up in some kind of blanket I had in the car. Then I turned the car heater to max and drove back to the Valley by which time all was well.
We the older living have to wonder occasionally how many times we should be dead by now.
Tom Higgins
LongAgo
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HighTraverse
Trad climber
Bay Area
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While he could just touch bottom being close to shore You guys were really lucky! Glad you both made it back
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divad
Trad climber
wmass
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depends on the lake...
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Mungeclimber
Trad climber
sorry, just posting out loud.
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Tom,
There are some great videos on youtube about how to escape from a punched hole in the ice, and helpful tools that provide a way to ease escape.
As to the OP, I'm not an expert, but I've heard the term of 4" and bonded to be able to support body weight.
Personally I like this kind of depth...
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east side underground
Trad climber
Hilton crk,ca
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Been skating on lakes for a long time now. Always bring ice screws, rope and axe ( inner tubes work as life preservers with rope attached). Years ago when we had the tragedy at convict lake we had been skating for a week on 4"-5" ice . All it took was a warm front with high winds to turn it from great skating to a death trap. That's when the kids went out on to the ice......
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SierraGoat
Trad climber
Quincy, Ca
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I recall that the key factor for ice to form is depth of the lake (and of course how long its cold for). The top of the body of water cools down to 4 degrees Celsius and then becomes denser and sinks to the bottom of the lake. This cycle then continues with the surface water until all the water of the lake is 4 degrees at which point the water on the top can then freeze. I am assuming that between 4 and 0 degrees the water molecules start to take on a geometry that then allows it to be less dense than liquid water. So deep bodies of water take a long time to freeze because the 4 degree cycle has to repeat so many times.
Our rule of thumb for skating has always been 1.5" if your daring and that 2" is pretty bomber. Of course if there is a huge increase in temp and sun exposure things can get kinda funny...
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LongAgo
Trad climber
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Rope, ice axe... very smart to bring on a frozen lake. In our fiasco I described where Tom G fell through into cold water, I believe my belt and a piton hammer with a pick end was involved in the haphazard extrication, with me crawling out lizard style toward Tom. As I say, pretty young and dumb, but alive to tell about it.
As to whether I would let my kid go out on such a lake in such a condition, no way. Fortunately, she was and is much smarter about such things than I was in the day.
Tom Higgis
LongAgo
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