If you take a glass of water from the sea, we will see a clear liquid there, but if you look deep into the reservoir itself, the water will turn blue. Why is the sea blue in one case and transparent in another?
The role of the atmosphere
It was once believed that the answer lies on the surface, and to be completely accurate, it reflects in it: the sky is blue. That is why the water in the sea is blue - it reflects the blue sky! Indeed, due to its chemical structure and physical parameters, water masses act as an ideal mirror, reflecting the visible color of the sky and cloud masses floating above it. Therefore, for example, the water of the Baltic and Mediterranean seas cannot be confused even in photographs. Indeed, gray-lead tones prevail in the Baltic Sea, and this is partly due to the fact that seventy-five percent of the time of year heavy dark clouds hang over the horizon. But in the southern latitudes the sky is mostly cloudless, and, reflecting, it gives the water a beautiful blue color.
But there are more significant factors. The fact is that light in water bodies refracts, and he does it at different angles at different depths. At shallow depths, the water will appear transparent due to the fact that rays of different colors and shades are refracted in it. They overlap each other, and as a result, our eye perceives water right near the shore or, say, in a glass, almost colorless.
Dependence on Depth
The greater the depth, the greater the difference in the time of absorption of the rays and their length. And there is another feature - only shades from the rainbow spectrum are absorbed and scattered. Yellows, oranges, and reds will dissipate on the surface, at greater depths the water will be green due to interaction with green hues, and the deep layers of the sea will absorb blue, blue and purple hues. That is why the sea of blue is far from the coast. It is thanks to this phenomenon of reflection and absorption of light that snow appears white - it reflects white, and ice reflects all colors, which makes it appear transparent.
Life takes its toll
But that is not all. After all, it is impossible, thoroughly answering the question why the sea is blue, simply to discount those who live there. For example, phytoplankton has a huge impact on the color of a reservoir. Because of the chlorophyll contained in it, phytoplankton absorbs blue rays and scatters green ones. Accordingly, the more this plankton itself, the more expressive will be the green color of water. However, in addition to phytoplankton, there are many other inhabitants of the depths that give the sea different shades. These organisms can be all colors of the rainbow, and their concentration directly affects the color of the water.
Another factor is the smallest particles suspended in water. To measure their quantity, as well as chemical composition, you can use a special device on the scale of chemical compounds created by Francois Trout. The chemical composition of the liquid plays a very important role in the coloring of the entire reservoir. In slightly salted and cool waters, blue and blue shades prevail, and in salty and relatively warm layers - green.
Mystery of the Black Sea
In order to understand why the rivers and seas are blue, consider an example of the Black Sea. In this connection, he was given such a descriptive name? Scientists on this score have two main hypotheses. Firstly, the sailors noticed that during the storm the water darkens and becomes almost black (although during the storm everything darkens, if you look closely, this is really so ...). Secondly, if you lower a metal object to a greater depth, it will darken. This will happen due to the content of hydrogen sulfide - a substance secreted by bacteria, the function of which is the decomposition of animal and plant corpses. And again, if you draw water into a glass, the liquid will still be transparent, but from a bird's eye view it will be blue.
The answer lies deep
To summarize, we can distinguish the following main factors that explain why the sea is blue:
- Physical. Refraction of sunlight and high temperatures give azure tones to the depths of rivers and lakes , however, the smaller the volume of water and degree, the more transparent the water will be.
- Biological. Phytoplankton, suspended particles, algae and microorganisms that live in the abysses of water, give the water green or blue shades of color.
- Chemical. If the red paint is mixed with water - there will be red water. Something similar happens with the sea: the chemical compounds that form in it under the influence of various factors give a color in different colors. Well, in fairness, we must add to this hydrogen sulfide, which colors everything that is not laziness in dark shades. We should not forget about the high salt content, which scatters the rays of the blue part of the spectrum.
Thus, such a seemingly simple substance as water in its various states of aggregation, having a completely different color, gives an abundance of questions. Like the dilemma “Why is the sea blue?”, They can confuse not only a child, but also a fully educated adult.