Why does hot water visually separate from cold?

In summary, the conversation discussed the observation of a rising volume of water around an electric heater in a fish tank. The participants considered possible explanations, including the difference in density causing the water to appear visually separated, similar to hot ground in the desert. They also discussed the potential role of a different refractive index in causing the shimmering effect above hot objects.
  • #1
billyboy223
2
0
Hey guys, I'm new to these forums so I'm hoping i have posted this question in the appropriate thread.

Recently, i noticed the electric heater in my fish tank had a volume of water around it all times which was rising, it made sense to me that the water surrounding the heater would be rising due to density, but the fact that it was visually separated to the colder water puzzled me. It was like the hot water appeared like alcohol, rising with swirls.

I asked my friend what he thought it could possibly be, and he said it appeared to have the same characteristics as hot ground does in the desert, shimmering above the surface as the hotter medium rises. But i was not convinced, i was thinking more along the lines that perhaps the hotter water had a different refractive index due to its decreased density, and in relation to the light shining upon it consequently appeared isolated.

I'm sure there is many people on here that have a greater idea than me as to why this happens, it would be great if you could help me out. Thanks.
 
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  • #2
billyboy223 said:
the hotter water had a different refractive index due to its decreased density
Pretty much :smile:
 
  • #3
mmmm, would this alternate refractive index also be the reason why the airspace immidiately above hot ground sometimes shimmers? Or is my friends opinion a different concept altogether?
 
  • #4
Nope, same concept.
 

1. Why does hot water rise and cold water sink when they are mixed together?

Hot water rises and cold water sinks due to differences in their densities. Hot water is less dense than cold water because its molecules are moving faster, creating more space between them. This creates buoyancy, causing hot water to rise and cold water to sink.

2. Why do hot and cold water not mix immediately?

Hot and cold water do not mix immediately because of convection currents. When hot and cold water are mixed, the hot water rises and the cold water sinks. As a result, a circular motion is created where hot water is constantly rising and cold water is constantly sinking, causing the two to take some time to mix completely.

3. Does the temperature of the water affect its viscosity?

Yes, the temperature of water does affect its viscosity. As the temperature of water increases, its viscosity decreases. This is because the molecules in hot water have more energy and move around faster, causing them to be less tightly packed together and flow more easily.

4. Why does hot water visually separate from cold water?

Hot water visually separates from cold water because of the difference in their refractive indices. The refractive index is a measure of how much light is bent when it passes through a substance. Hot water has a lower refractive index than cold water, causing light to bend less and making the two appear to be visually separated.

5. Does the separation of hot and cold water have any practical applications?

Yes, the separation of hot and cold water has been used in solar water heaters. The hot water is lighter and rises to the top of the tank while the cold water sinks to the bottom. This allows for the hot water to be easily drawn from the top of the tank, making it more energy-efficient and cost-effective.

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