Water Temperature Physics

[bygolly]

I have seen many posts on this website with people claiming they dove in 33-38 degree fahrenheight (0.5-3.3 degrees celcius) water in a lake or quarry in the middle of the summer. I would like to point out that this is impossible. Water reaches its maximum density at 4 degrees celcius (39.2 degrees fahrenheight), and if there was something at depth to make it colder (which there isn't), it would simply rise to the surface, and warm up. In the winter time, water below 4 degrees celcius rises and freezes, and water at 4 degrees celcius sinks to the bottom. This is why the water very deep in a freshwater quarry or lake is exactly 4 degrees year round, and can never be any colder.

But it is so much more fun to exaggerate just a little bit....EVERYONE knows that.

 

[Doppler]

Both my Suunto D3 and Cressi-Sub Archimedes II read a minimum of 37 degrees F after a 40 minute dive at 25 feet.

The dive manuals for both instruments indicate temperature accuracy +/- 2 degrees C (3.6 degrees F) within 20 minutes of temperature change.

So if we are to believe windapp, both instruments, made by two different companies, were off by exactly the same number of degrees, and the error was in the same direction.

Can someone here with a degree in statistics give us a p value for the likelihood of such an event?

Sounds like the stats falling into the realm of the Chance Brothers; Slim, Fat, and Nun.

 

[Thalassamania]

Have you tasted sea ice?

Yup. New sea ice is usually very salty because it contains concentrated droplets called brine that are trapped in pockets between the ice crystals, and so it does not make good drinking water; but as ice ages, the brine drains through the ice, and once it is multiyear ice, most of the brine is gone. Most multiyear ice is fresh enough that you can drink its melted water. More than a few polar expeditions survived on it.

Ice that is calved off a glacier is all fresh water.

 

[dumpsterDiver]

The OP is correct and this should have been taught in high school . People will argue with anything...3.98 C baby

Q: Where do you find the most dense water?
A: At the bottom of the quarry

Q: where do you find the most dense divers?
A: Here; it seems..

 

[jimthediver]

The OP is correct and this should have been taught in high school . People will argue with anything...3.98 C baby

Q: Where do you find the most dense water?
A: At the bottom of the quarry

Q: where do you find the most dense divers?
A: Here; it seems..

Now that's funny!

 

[windapp]

I can't argue with you there bygolly. Both my sons now that every fish they catch was as big as they can convince someone it was.

 

[markr]

... and if there was something at depth to make it colder (which there isn't)...

What if there were a cold spring in the deepest water of the quarry? You could have cold water entering creating a localized cold spot. The deepest part of some quarries is relatively small compared to the overall surface area, while the water would rise and warm as it approached the surface, it might be possible to get an area colder then what the physics you using would normally allow.

I've heard that it can be proved that bumble bees can't fly. It was also believed that nothing could live in the volcanic vents in some of the oceanic trenches, and yet life as been found there.

 

[windapp]

What if there were a cold spring in the deepest water of the quarry? You could have cold water entering creating a localized cold spot. The deepest part of some quarries is relatively small compared to the overall surface area, while the water would rise and warm as it approached the surface, it might be possible to get an area colder then what the physics you using would normally allow.

I've heard that it can be proved that bumble bees can't fly. It was also believed that nothing could live in the volcanic vents in some of the oceanic trenches, and yet life as been found there.

Spring water is subject to the same physical laws. Therefore, no such thing as a less than 4 degrees celcius spring at the bottom of a quarry. The fact is, that unless you are in a melt lake on top of a glacier (which you would be nuts to dive in anyway), there is nothing at depth that is that cold.

The properties of water are well known, and as of today, undisputed. It s not a belief. It is verifiable fact.

By the way, the bumble bees can't fly thing is foklore. It has never actually been suggested in real scientific or engineer circles.

 

[txapacheguy]

Interesting thread. I was kind of wondering why my nitek duo registered my ice dives this winter between 39 and 40 degrees Fahrenheit... Makes sense I suppose.

 

[irishsquid]

...in a freshwater quarry or lake ...

This is what I have trouble with. I WISH I could find one of these.