Ice Diving Water Temps

[mavdog]

The melting point of water at 1 atmosphere of pressure is very close to 0 °C (32 °F, 273.15 K), and in the presence of nucleating substances the freezing point of water is close to the melting point, but in the absence of nucleators water can supercool to −42 °C (−43.6 °F, 231 K) before freezing. Under high pressure (2,000 atmospheres) water will supercool to as low as −70°C (−94°F, 203 K) before freezing. I Google Search supercooled water and found this on wikipedia

 

[KOMPRESSOR]

I thought there might be the possibility of a "reverse thermocline" (for lack of a better term) in a deep lake in the winter, but this article supports your statement.

The Great Lakes Atlas: Chapter Two

Kind of interesting reading too.

I saw that before, but only the first chapter! I didn't realize there were several chapters...

Reverse thermoclines happens in the ocean in our fiords during heavy rainfall in the winter. "Light" but cold freshwater floats on top of warmer but heavier seawater. I've had surface temps of 34-35F when diving, thermocline at around 20ft, and then 46-47F at depths down to 75ft before it got colder again. (Guess what, 39F...)

 

[Busdiver]

The other day the St. Clair river in Michigan read 40 degrees at 23 feet. My body was warm but my face had a chill. I will let you all know if I am hit with any blocks of ice if the water drops below 32 degrees. Retro, come for a dive in the swift currents.

 

[boat sju]

Retro, come for a dive in the swift currents.

If you're willing to "guide". I have a fear of missing the exit point and having to walk two miles back to the car. But it won't be until next summer anyway, because I don't have a drysuit.

I'm kind of surprised we haven't run into each other in Monroe.

 

[Notso_Ken]

35F = 1,7C. Rounded up it's 2,0C, which means your gauge only had to be 2C off to show what you got IF water temperature was 4C. -Which to me seems fairly likely. I've seen computers more off than that several times.


Sincerely,

Retro's "jerk"


PS! I am really sorry to have offended you, as I apparently have. It's just so obvious to me that water is at it's densest at 4C/39F and that ordinary freshwater in a lake for all practical (scuba related) reasons will freeze at 0C/32F, and I have yet to meet a scuba diver who questions this.

Yes, water is at it's densest at approximately 39*F, so that will sink to the bottom. However, once all the water is 39*, or colder, and it is colder than that around the body of water, then the water that is 39* will start cooling below 39*. The densest water will stay at the bottom, but it can and will be colder than 39* in northern climes in the winter. (Actually, the coldest water I have seen is actually in the early spring, before the weather is warm enough to start warming it up. Think April!)


Ken

 

[KOMPRESSOR]

Yes, water is at it's densest at approximately 39*F, so that will sink to the bottom. However, once all the water is 39*, or colder, and it is colder than that around the body of water, then the water that is 39* will start cooling below 39*. The densest water will stay at the bottom, but it can and will be colder than 39* in northern climes in the winter. (Actually, the coldest water I have seen is actually in the early spring, before the weather is warm enough to start warming it up. Think April!)


Ken

What do you mean by "northern climes" then? How far north?

There's no saying it WILL be colder than 39F. But under certain conditions it can. This will likely be in shallow waters, lakes with large water surfaces where wind can pick up and thereby set the water masses in sirculation and push cool surface water down. But these are rather the exceptions than the rule.

By the way, I live at N60 37.279 and I've been diving at N70 23.264. Would that be "northern climes"? It doesn't get below 39F on a regular basis at the deeper parts of medium or large sized lakes here.

 

[Bob3]

I've spent way too much time in fast moving 28°f water in the Missouri River just upstream of the Mississippi River confluence. Had one of those double-digit below zero cold snaps that lasted for a couple weeks.
Also been in a harbor on Lake Michigan where it was that low after a couple weeks of storms & heavy surge. It was the 2nd week in Feb. during one of those nasty cold spells.
All the straps & hardware freeze up near instantly of leaving the water so ya don't want to hold off taking a leak for too long, it can take a while to thaw the zippers & etc, especially when the diver is doing a little "gotta go" dance.:11:

 

[Notso_Ken]

What do you mean by "northern climes" then? How far north?

By the way, I live at N60 37.279 and I've been diving at N70 23.264. Would that be "northern climes"? It doesn't get below 39F on a regular basis at the deeper parts of medium or large sized lakes here.

You qualify as northern!

 

[SwimJim]

Thanks for posting the video on the Walter B. Allen Kompressor. It's a shame the main mast is down. I see the hoops are still there at least. I love that wreck. FWIW I was diving the Northerner off Port Washington on January 1st 2006 and recorded 30 degrees on both my computer and my spg. Call it what you want, it was damn cold. That dive convinced me to get dry gloves for the dry suit. My "ice diving" has been on inland lakes and it's usually warm under the ice. More like about 35 or so.

Jim

 

[KOMPRESSOR]

Thanks for posting the video on the Walter B. Allen Kompressor. It's a shame the main mast is down. I see the hoops are still there at least. I love that wreck. FWIW I was diving the Northerner off Port Washington on January 1st 2006 and recorded 30 degrees on both my computer and my spg. Call it what you want, it was damn cold. That dive convinced me to get dry gloves for the dry suit. My "ice diving" has been on inland lakes and it's usually warm under the ice. More like about 35 or so.

Jim

It seems those Great Lakes are really cold lakes in the winter. I have a theory that since they are so huge across, winds can circulate a lot of water which again will push cold surface water down to to greater depths than most other places before the lakes actually freeze up. So you will have a deeper thermocline there than in smaller lakes when the ice finally sets. Could that be right?

Anyways, I'm retiring my neoprene 3-fingers for the season and investing in some Nordic Blues! We're having the open water dives with 19 OWD-students next week, and it's friggin' cold out there now!!!

Since you Great Lakes fans have your own subforum here at Scubaboard I think I'll slip in some impressions from one other great lake here where I live! Here's boat that actually was saved off the bottom of our lake some years ago. It would have been a hack of a diving site at 100ft, but I feel it's better of on the surface:

Video: Video på nett: In2it media - 991 58258

More info: Skibladner: the world's oldest paddle steamer