Some bodies of water seem green to us, others blue, others blue. Water collected in a transparent container is transparent. Why is the sea blue? In order to put everything in its place, consider the physical properties of water.
Water color
Pure water is blue. 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 glass aquarium with water, the blue color will become visible to the naked eye.
What affects the shade? The human eye sees reflected light rays, so it is important which of them the substance absorbs and which reflects. The spectrum of visible sunlight consists of all the colors of the rainbow.
The water molecule absorbs the red and green parts of the spectrum, and reflects the blue. This gives the water a bluish tint. The thicker the layer of water, the more intense its color.
Natural waters
This is in theory the color of water is blue, in nature, pure and identical colors are rare. Why is sea water blue? Away from the coast, the oceans and seas have great depth and seem to the observer black and white.blue or purple. Closer to the shore, the water becomes lighter: bluish, greenish, aquamarine, etc.
Why is there such a difference? The intensity of color and shade is influenced not only by the thickness of the water layer, but also by the presence of suspended particles. Off the coast, in the pelagic layer, there are many algae and biological remains. Some of them enter the seas from land. Phytoplankton are green because they contain chlorophyll. It reflects the green part of the spectrum and absorbs the red and blue. The presence of algae determines the greenish nature of the hue of coastal waters.
Depth and color
The depths of the sea and sandy deserts have much in common - there are very few living creatures in them. Satellite images clearly show 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 great depth. Along the coastline, the color of the water is greener, hence, there is a large number of marine life. In the blue depths, biodiversity is poorer, like hot desert spaces.
To answer the question why the sea is blue, consider the change in color of an object immersed in it. The yellow submarine at the surface will appear to us as it really is.
The deeper it sinks, the harder 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 those in it.particles of animate and inanimate nature.
At a depth of thirty meters, the submarine will already appear bluish-green to the observer. This is due to the fact that most of the yellow-red spectrum will be absorbed by water. When it is several tens of meters lower, the water molecules will also absorb the green spectrum. As a result, the yellow submarine will take on a dark blue hue.
The ocean contains many more suspended particles than 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 s alty and does not have the ability to glow. Everything that is visible under its surface looks like this in reflected sunlight. I wonder why 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 share of radiation falls on the yellow-green segment of the visible spectrum. The color of the sea depends on which part of the spectrum is reflected and which is absorbed. This complex mechanism was described in detail by the geophysicist V. Shuleikin at the beginning of the 20th century.
The molecules that make up the ocean oscillate and rotate at different rates, which affects reflectivity and absorptivity. They easily absorb red rays and reflect blue ones. For this reason, observers above the sea see it as bluish or purple.
Red rays are absorbed at the first meters of depth, green - closer to 100, and blue - only at the second or third hundred.
Transparency of the seas
Transparency of water in the world's 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, mud and suspensions of various substances. Least of all benthic unicellular organisms are found off the coast of about. Easter. Therefore, the waters there are the most transparent compared to other parts of the World Ocean.
The seas are scattered all over the surface of the globe. Some of them are located in the tropics, the other - in the zone of the poles. Over some, there is mostly heavy rainfall and few sunny days. 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 as seen by the observer.
Thus, having studied all the physical properties of water, we can now confidently answer the question why the sea is blue.
