24 days of kitchen oceanography
Each day a new experiement will be posted here. Reveal what is hidden behind the windows by clicking on the arrows below.
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Temperature, salinity and density
Why does the meltwater of pink ice cubes stay close to the bottom in one of the glasses, and raise to the top in the other?
Experiment 23:
We fill two glasses with water, the left one with fresh water, the right one with salt water, all at room temperature. Two colored ice cubes of similar sizes are “forced” to the bottoms of the glasses (for example by placing them into tea sieves), where they start to melt. The melt water has about 0°C.
Due to the different temperatures of the water, as well as the different salinities of the two glasses’ original contents, there are three different densities present in our experiment now. The salt water at room temperature in the right cup has the highest density. The colored, cold melt water raises and forms a layer on top of it. But the cold melt water has a higher density than the fresh water at room temperature in the left cup, so it stays near the bottom in that glass.