December 18, 2011 0:34
Photo — the Strait of Gibraltar, connecting the Mediterranean Sea and Atlantic Ocean. Water seems divided between the film and have a clear line. Each of them has its temperature, its salt composition, animal and plant life.
Earlier, in 1967, German scientists have identified the fact nesmesheniya water layers in the Bab el-Mandeb, which converge water Gulf of Aden and the Red Sea, the Red Sea and Indian Ocean. Following the example of their colleagues, Jacques Cousteau was to find out whether the mixed waters of the Atlantic Ocean and the Mediterranean Sea. First, he and his team investigated the water the Mediterranean — its natural level of salinity, density, and the inherent life-forms. Did the same in the Atlantic Ocean. These two bodies of water are found in the Strait of Gibraltar for thousands of years and it would be logical to assume that the two huge water masses long ago should have been mixed up — their salinity and density were to be the same, or at least similar. But even in places where they meet the closest, each of which retains its properties. In other words, at the confluence of two bodies of water water curtain did not give them to mingle.
If you look closely, in the second picture you can see the different colors of the sea and on the ground — a different wavelength. And between them, as if an impenetrable wall.
The point here is the surface tension:
Surface tension — this is one of the most important water parameters. It determines the strength of coupling between the molecules of the liquid and the shape of the surface at the boundary with air. It is due to the surface tension of the drop is formed, puddle, stream, etc. The volatility (volatility) of any liquid, too, depends on the forces of adhesion molecules. The lower the surface tension, the more volatile liquid. The lowest surface tension have alcohols and other organic solvents.
If water had a low surface tension, it would quickly evaporate. But the water is still quite a large value of the surface tension.
Visually, the surface tension can be expressed as follows: if slowly pour in a cup of tea to the brim, then for a while it will not spill out through the rim. In transmitted light, you can see that the surface of the liquid formed a thin film, which does not pour tea. It swells as topping and only, as they say, with the "last straw" liquid poured over the edge of the cup.
And the waters of the Atlantic Ocean and Mediterranean Sea can not mix. The value of the surface tension is caused by varying degrees of density of sea water, this factor, like a wall, which prevents the mixing of waters.