# is cold water denser than warm?

In the news coverage of the airliner landing in the water in New York last week, I heard an “expert” say that they were fortunate the water was cold, otherwise the plane would have sunk faster instead of coasting smoothly to a stop. My jaw dropped when I heard that. My kayak workout speed always drops this time of year, but I always thought it was because of too much holiday cheer. How 'bout it waterpeople, is cold liquid water really harder than warm water? Is that what is slowing me down?

Here be de lowdown…

– Last Updated: Jan-17-09 4:19 PM EST –

Dependin' on salinitee...

Temp (°C) Density (kg/m³)
+100 958.4
+80 971.8
+60 983.2
+40 992.2
+30 995.6502
+25 997.0479
+22 997.7735
+20 998.2071
+15 999.1026
+10 999.7026
+4 999.9720
0 999.8395
−10 998.117
−20 993.547
−30 983.854

http://www.csgnetwork.com/h2odenscalc.html

cold air denser too
so don’t forget the added wind resistance.

Appropriate use of quotes, I think
I’m often amused by so-called expert commentary like that too. Fat Elmo beat me to posting the actual relationship of water density to temperature, but to put his table in perspective using units we in the U.S. are more familiar with, a cubic meter of water weighs roughly 2,202 pounds, but the change in the weight of that meter of water from 15 degrees C to 4 degree C (that’s a useful range to compare in this case, and sorry I didn’t change it to degrees F)is about 0.2 pounds. That’s not much, and surely not enough to make a difference that anyone could have noticed in this case.

So let me get this right
Cold water becomes more dense. Once frozen, it becomes less dense since it floats???

some of the people around this website certainly are much more dense in cold weather.

yes
The atoms get closer together as they slow down (colder water), but when they lock into an ordered crystaline matrix, they take up more space because of constraints of that crystal structure.

Yes
Cold water is denser than warm water.

Yes, the “expert” is an idiot.

yeah
If it were significantly more dense, water levels would drop significantly as the water got colder, and rise significantly as the water got warmer.

Water is an exception to the rule,
most liquids continue to become more dense as they get colder and even when they freeze. Water is most dense at 4 degrees C as posted above and indeed this is why ice floats.

They large volume of air in the cabin and lower compartments as well as the fuel tanks are what kept the plane afloat so long. We;; that and the fact that it didn’t bust open when it hit the water.

jim

ice
in a nutshell, ice is mostly air , thats why it floats

density

i was thinking , since its a proven fact that atoms slow down as they get colder, could it be that cold water moves slower , ie: it takes the water molecules more time to move out of the way and this is what slows down a object in cold water ? I’m not a scientist or a hydrologist but it’s known everything slows down the colder it gets, the answer to why you slow down in cold water probably lies on a molecular level, also your own muscles do not operate at peak in cold temps. also i was thinking …is there more “sticktion” from cold water than warm water? i know the colder it gets the slower i get! if you take it to a extreme …cold, slushy water does not flow as easily as warm water. i tried to google up a better answer and didn’t get much.

That’s a joke, right?
I sure hope so.

I’ve noticed that cooler water tends to be slower, too. Also, wearing bundles of clothing in the winter restricts movement, especially neoprene gloves and westsuits. The “experts” - elite paddlers will confirm that cold water is slower paddling than warm water. I don’t understand the complete factors. Also, warm salt water is faster paddling than a similiar temp freshwater. A major speed limitation is shallow water - generally less than .5 waterline length will slow you down. As the water gets down to less than 5-6 feet, it becomes very rapidly more difficult to maintain speed.

Viscosity
Water that is about 35 degrees is about twice as thick as water that is 75 degrees. It is easy to test the viscosity for yourself with simple equipment you can make.

The difference in density or weight per unit volume across the temperature range is very slight, but the viscosity difference is huge.

People naturally understand this with honey or oil, but since water still pours well out of a pitcher when is is icy, folks don’t think of it as being thicker, but it is.

Hot water tank…
…from olden, or modern if you have the stove for it, days is a good example. Pipe comes from bottom of tank into stove, where water warms it, water expands so same amount of water is lighter and rises, and travels up the pipe to the top of the water tank and is replaced by the cool water that keeps coming in from the bottom of the tank. After a while the water in the top of the tank gets so da\$%#& hot that it starts to boil unless you drain it off.

Water as it cools continues to contract, or get more dense, until the point where it solidifies at which time it expands slightly. Good example is those in the frozen north who forget to put antifreeze in their car/truck/etc. cooling system. Result is cracked rads, busted engine blocks from the solid water expanding as it freezes, and then again as it starts to melt.

However, Elmo has the numerical proof.

Only as it freezes initally

Everyone knows …
… that a polyethylene beverage bottle, even one filled to the brim with water, will float in a lake, as the plastic itself is slightly buoyant. So imagine my surprise last summer when my freshly filled water bottle slipped from my deck bungees and promptly sank like a stone.

All I can figure is that the very cold tap water with which I’d filled the bottle was denser than the lake’s surface water, lending it enough negative buoyancy even to offset the buoyancy of the plastic bottle, and taking the whole works down. (Note that there was NO air space inside the bottle.)

I presume that the bottle continued to sink until it reached deeper waters cold enough to match the density of the water in the bottle, where it stopped. Probably when the water temp inside the bottle equalized with that of the surrounding lake water, the buoyancy of the plastic bottle was enough to raise it a little higher, whereupon it equalized with the slightly higher and warmer water, and so on until it slowly and finally reached the surface, buoyed only by the plastic of the bottle itself.

I didn’t wait around long enough to see …

Delphinus

perhaps this will help answer some …
… of the questions regarding water in reference to it’s temperatures and weight variations .

(bear in mind that different waters will have different specific weights depending on compositions … example being sea water compared to fresh water , etc.)

http://www.engineeringtoolbox.com/water-specific-volume-weight-d_661.html

now viscosity and hydrostatic properties of water can become much more brain twisting when attempting to relate how those properties affect a paddler with a paddle .

http://en.wikipedia.org/wiki/Viscosity

Delphinus , love the bottle example !!