why doesn't the water in water towers freeze?
480396
Ohhhh No. it will freeze. It just won't freeze as easily as others because water has very high heat capacity compare to many surround things, which means it takes longer to cool down or heat up. Let's say it's -20 degree C at night but at dawn to dusk it might not be. So water in the tower spend more times under tempreature above 0 degree and less time under tempreature under zero. (imagine) Let's put that tower in artic region where everything is frozen all the time. What do you think.
1156112
You will probably have to mix the water with another substance, or use an entirely different substance for it.\n\nThe fusion of a substance can never change - it can only be maintaned. By mixing water with a substance with a better fusion point, it will keep the water frozen for a longer period.
40258
Some models in addition utilize compressed air to atomize  the water.  Most though simply utilize fogging high pressure mist into freezing air.  Collision in the air of two streams of water is another means of breaking the water into small dropletts which will freeze before hitting the ground, this actually requires less energy on the parts of the electric pumps ie lower pressure and higher volume of flow.
552808
Write your own essay...but water freezes when it is cold and becomes ice which expands causing the pipes to burst, that's why they need lagging/insulating to prevent this happening.
339414
some reactors don't need them b/c they're not cooled by water.  they have liquid metal reactors and also gas cooled reactors.  however.  however, in a boiling water reactor the water that turns the turbines never comes in contact w/the outside, it simply stays in the reactors in a continuous loop.  that heated water is used to boil other water which causes the turbines to turn.  pretty much all of the reactors used in the United States are PWR so they all will have cooling towers.
731331
I've heard that its the boiling water that freezes first. \n\nI think because the water molecules are hot (i.e. they are moving fast) the energy (or heat) will escape (move to equilibrium with other items in the freezer) at a faster rate than the water molecules in colder cup of water. \n\nBut really I'm mostly guessing with my explanation.
118956
Liquids expand when they freeze.
1163536
The definition of freezing is that they reach 0C, not that they turn to a solid, that is a separate step.  Hot water pipes and cold water pipes, both in an identical freezing environment will cool down at different rates because the higher the temperature gradient or difference, the faster the rate of cooling.  So hot water will cool faster to 0 than cold water, although cold water will form ice faster since overall it requires less heat overall to be removed to freeze.\nNote that practically the hot pipe will take longer to freeze solid since there simply needs to be more energy removed to get the solid.  This question is normally asked theoretically to demonstrate (or trick a student) to teach the lesson about how larger temperature gradient have a higher cooling speed relative to the lower temperature gradient.  It depends on the reason for asking this question.\n\nNote that the Mpemba effect, while it has been observed, is only under specific experimental conditions and is far from a general phenomenon and not general enough to effect the average set of pipes in the average house basement.
17885
In Saratoga Springs, NY where it can get very cold (and Olmpic Speed Skaters have competed on an oval rink) the ground is sprayed with water and allowed to freeze in a natural shallow basin that was bulldozed into an oval track with land in the middle.  Water can then be sprayed on top of the original ice layer to thicken it without melting through.  When the ice layer is thick enough, the entire area can be slowly flooded.  The water used is at groundwater temperature from a hydrant using a fire hose.  I believe that groundwater is about 46F here but will vary from city to city as it is basically the average temperature of all the water that seeps into the ground during a typical year.  The lowest temperature of drain water is of course 32F.  Thus the water is only 14F warmer than the ice being layed down and it must be well below freezing to prepare the rink.  A hockey rink could be built the same way by omitting the land in the middle; but it would require more water.\n\nOf course, ice rinks can be located on a lake or pond if it freezes thick enough.  The NY State Park here has a special rectangular rink that merely requires flooding for figure skating and recreation.
233535
i always thought it was because there was no humidity in the air...probably wrong, anyway. or maybe its because the warm climate doesnt allow the moisture to turn back into water. who knows? prob a weatherman.
196823
The fact that ice always floats on water should give you a clue!  The ice is obviously not as dense.  So you can infer from this something has happened during the freezing process.\n\nThe structure of a water molecule is One atom of hydrogen to two if oxygen.  As the water freezes hydrogen bonds form between the various water molecules and these stop the molecules packing as effectively so the ice is less dense.\n\nTry the source below.
291269
Cold water has more dissolved gases in it than hot water.  Any dissolved solutes cause the freezing point of water to be lower than pure water with nothing dissolved in it.\n\nThis means if your power goes out in the wintertime and it is about 32 degrees F outside, the water in your hot water pipes is more likely to freeze than the water in your cold water pipes.  This is because the freezing point of the water in your hot water pipes is higher than the freezing point of the water in your cold water pipes.\n\nSpeed isn't being considered here.  The cooling process is assumed to be slow so that the pipes are in thermal equilibrium with surroundings.\n\nAlso check out this link.  It is from the Alaska Science Forum.  They can explain the water pipes problem more correctly than me and they have more personal experience with the phenomenon.\nhttp://www.gi.alaska.edu/ScienceForum/ASF4/440.html
807422
When water freezes, it expands because the molecules form into a crystal lattice. The expansion causes ice to be less dense than liquid water and as a result, it floats.
215641
Usually, when a pond freezes, it does not freeze totally solid.  Due to some rather nice properties of water, the pond will freeze from the top down leaving the fish with an area below the ice to swim around it.\n\nDue to fact that water expands when it freezes (because of the intermolecular forces at work), ice floats in liquid water.  Similarly, when pressure is applied to ice, it melts since it is trying to relieve the pressure on the system and this can be done by reducing the overall volume by melting.
825292
i guess I'm wrong   but I thought that water would  freeze at 0  degrees celsius.  also it would boil at 100 degrees C. Even in a vacuum.  my guess!  btw at absolute 0  kelvin,  does that only exist in a vacuum?  If we could reach  - 450 degrees F.  would our cpu's operate at an infinite speed.....got me on this one.  I'm not sure on how atmospheric pressure relates to these conditions.  But I know someone knows!
347092
Many (square?) cooling towers are open on all sides through wooden or fiberglas slates that allow air to enter and mix with the sprayed water to be cooled.  The water droplets partially evaporate giving up much of their heat then fall to the cooling tower basin below the tower where the "cooled" water is pumped back into the plant to extract more waste heat.  The water is recycled perhaps to extract heat from giant condensers to create very low pressures (partial vacuums) at the turbine discharge permitting the turbine-generate to generate far more electricity than if the turbine discharged directly to the atmosphere.\n\nHyperbolic (hour-glass shaped?) cooling towers perform the same function and likely are more expensive to build than cylendrical (or square) cooling towers but the advantage is that all air enters at the bottom of the cooling tower (not through the sides) and passes up through the entire tower height producing a "chimney" effect that strengthens the draft promoting better heat rejection.  The reduced diameter would increase air velocity (like a ventouri tube) to counter the downward pressure of the water drops.
247767
Water can be compressed, when you compress something it cools, so when you compress water fast enough or with enough pressure it will just freeze.