Some bodies of water seem green to us, others blue, and others blue. Water drawn into a transparent container is transparent. Why is the sea blue? In order to put everything in its place, we consider the physical properties of water.
Water color
Clear water has a blue color. However, the intensity of the shade is so small that it is impossible to notice it in a small container. If you fill a large aquarium with glass with water, then the blue color will be visible to the naked eye.
What affects the hue? The human eye sees reflected light rays, therefore it is important which of them absorbs and which reflects. The spectrum of visible sunlight is made up of all the colors of the rainbow.
The water molecule absorbs the red and green parts of the spectrum, and reflects the blue part. This gives the water a bluish tint. The greater the thickness of the water layer, the more intense its color.
Natural ponds
This is, in theory, the color of water is blue, in nature pure and the same colors are rare. Why is the water in the sea blue? Far from the coast, the oceans and seas are deep and appear to the observer black-blue or purple. Closer to the shore, the water becomes brighter: bluish, greenish, aqua, etc.
Why is there such a difference? The intensity of color and hue is affected not only by the thickness of the water reservoir, but also by the presence of suspended particles. Off the coast in the pelagic layer are many algae and biological residues. Some of them fall into the sea from land. Phytoplankton is green because it contains chlorophyll. It reflects the green part of the spectrum, and absorbs red and blue. The presence of algae determines the greenish nature of the shade of coastal waters.
Depth and color
The sea depths and sand deserts have much in common - they have very few living creatures. Satellite imagery clearly shows which seas are rich in living organisms and which are not.
Why is the sea blue, and not, say, green? Since in the center these reservoirs have a great depth. The water color is greener along the coastline, therefore, there are a large number of marine inhabitants. In the blue depths, biological diversity is poorer, like hot desert spaces.
To answer the question why the sea is blue, consider the color change of an object immersed in it. The yellow submarine at the surface will seem to us what it really is.
The deeper it sinks, the more difficult it is for the sun's rays to reach it. With each meter, the amount of light reaching its surface decreases, which is associated with the reflectivity of both the water itself and the particles of animate and inanimate nature that are in it.
At a depth of thirty meters, the submarine will appear to the observer already bluish-green. This is due to the fact that most of the yellow-red spectrum is absorbed by water. When it is several tens of meters lower, water molecules will absorb the green spectrum. As a result, the yellow submarine will acquire a dark blue hue.
The ocean contains much more suspended particles than in pure water. At the same depth, in the first case it will be much darker than in the second.
Light rays in the ocean
Sea water is salty and does not have the ability to glow. Everything that is visible beneath its surface looks like this in reflected sunlight. I wonder why the rivers and seas are blue, because daylight is not blue? At the surface, the spectrum of sunlight is almost the same as above water.
The maximum proportion of radiation falls on the yellow-green segment of the visible spectrum. The color of the sea depends on which part of the spectrum reflects the rays and which are absorbed. This complex mechanism was described in detail by geophysicist V. Shuleikin at the beginning of the twentieth century.
The molecules that make up the ocean oscillate and rotate with different intensities, which affects the reflectivity and absorption. They easily absorb red rays, and blue reflect. For this reason, observers above the sea see it as bluish or purple.
Red rays are absorbed in the first meters of depth, green rays are closer to 100, and blue rays are only in the second or third hundred.
Transparency of the seas
The transparency of water in the oceans depends not only on the physical properties of the liquid, but also on the organisms and particles contained in it. Turbidity is created by planktonic creatures, dirt and suspensions of various substances. Least of all benthic unicellular is found off the coast of about. Easter. Therefore, the waters there are the most transparent in comparison with other parts of the World Ocean.
The seas are scattered over the entire surface of the globe. Some of them are in the tropic zone, while others are in the pole zone. Above some, heavy rainfall and few sunny days fall. A number of seas are located in arid regions with a high intensity of solar radiation. These indicators also affect the color of the sea visible to the observer.
Thus, having studied all the physical properties of water, it is now possible to answer with confidence the question why the sea is blue.