Sea color, is the water transparent?
Why is the sea blue? Many people have asked this question more than once. Assuming that the water is clear, why do we see those beautiful turquoise hues?
People have heard that is because the sea is the reflection of the sky. But what happens when the sky is cloudy? The sea is still blue, right?
The explanation for this is given by the so-called Rayleigh scattering, named after the British physicist and Professor Lord Rayleigh (John William Srutt, third Baron Rayleigh), awarded the Nobel Prize in Physics in 1904. This theory states that electromagnetic waves comprising visible light penetrate transparent bodies, and when hitting small particles, it results in a separation of different frequencies of the light. Some of these frequencies are absorbed by water particles (red and orange), while others are reflected (green and blue). Those reflected are precisely the ones can be seen by our retina due to objects show just the unabsorbed color instead of the absorbed one.
There are other factors that have a bearing on the color of the sea such as underwater vegetation, animals, the suspended particles, salinity, microscopic organisms or water pollution. It is not difficult to find areas where the sea is greenish or reddish and this is mainly due to existing algae. One of them, Posidonia, is responsible for cleaning coastal waters by making them look much clearer.
As examples of seas of colors we can refer to the Red and the Yellow Sea. The fi rst one bathes the shores of Egypt and although, there are several theories about its hue, one of them supports that red algae stains the water with that color in some seasons. Meanwhile, the Yellow Sea in China, owes its name to sand particles of the same color that paint its waters. A clear example of algae infl uence on water coloration is that this sea suffered an invasion of green algae in 2013 and turned waters into that color.
But, why are different hues in the water? Besides seabed (vegetation and even sand and rocks) the position of the sun is determined, as sun’s rays are reflected at different angles. Depending on the amount of radiation the water absorbed, we can observe some colors or others. The intensity of light also influences as well as the presence or absence of clouds in the sky.
Another factor to be considered is the depth. As is deeper, more water will be, so the light will penetrate less into the aqueous medium and blue color will be darker. Hence the predominant color is dark blue at open sea, while green and turquoise hues will be found on the shore, very characteristic of tropical and heavenly beaches in which white sands also contribute to color.
The main colors of the Caribbean Sea are navy blue, turquoise or deep green which make the Dominican Republic to become one of the most idyllic locations. Whether it’s the refl ection of the sky, algae, salinity or white sand beaches, the fact is that the sea has color before our eyes. A hue going from shore to deeper waters but always brings that effect of peace and quiet with an amazing beauty.
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