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Warmer water allows sound to travel faster.

Yes. Sound travels a bit faster in warm water than it does in cold. At first glance, this seems illogical because the molecules are actually closer together in cold water than they are in warm, making it seem like it would be easier for sound to travel between them. But the critical factor in the speed of sound in water is actually the temperature—the higher temperature of the molecules creates a medium that allows sound to travel faster. Keeping salinity and pressure constant, sound travels about 15 feet per second faster for every 1.8 degree Fahrenheit rise in temperature.

Knowing how the speed of sound changes with water temperature allows scientists to measure the oceans' temperature, which may help determine whether the accumulating greenhouse gases in the atmosphere have raised global temperatures.

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