Why Is Seawater Blue?

At some point nearly every child with an inquisitive mind will ask

an adult why the sky is blue or why the seawater is blue. In a

simple sense, seawater is blue because is it a reflection of the

color of the sky above, but then why is the sky blue? The answer

lies in phenomena called scattering of light. Sunlight that enters

the atmosphere contains the complete visible spectrum of colors,

defined by different wavelengths. As this light enters the

atmosphere it encounters air molecules of oxygen and nitrogen,

each of which is smaller than the wavelength of visible light.

These molecules cause the incident light to be scattered when

the light hits them, but since the molecules are small they are

much more effective at scattering the short wavelengths than

the long wavelengths, which tend to pass over the small

molecules. This selective scattering is analogous to ocean

waves that encounter a buoy in the water. Waves that are small

(short wavelength) and about the same size as the buoy will

bounce off and be scattered by the buoy, but large waves (long

wavelength) will pass right by the buoy and hardly be affected.

Similarly, the shorter visible wavelengths of light, including violet,

blue, and green, are scattered efficiently by the small air

molecules, whereas the longer wavelengths of yellow, orange,

and red are scattered very little. The atmosphere scatters blue

light about 16 times as much as red light. The result of this scattering

is that as we look at the sky, we see blue light coming at us

from virtually all directions. In contrast, the yellow, orange, and

red light are not scattered effectively and appear to be only coming

nearly directly from the direction of the Sun. The same effect

causes distant mountains to appear blue, when scattering by

small particles is strong near the ground. The presence of larger

particles can cause different color sensations. For instance, the

presence of larger aerosol pollutants causes a brownish smog

color, and the presence of even larger water droplets causes

clouds and haze to appear white.

Most of the light and energy from the Sun that strike the sea

is absorbed by seawater and converted to heat, but some is reflected.

The upper surface of the sea reflects the color of the sky, which

is most often blue. However, the presence of suspended particles

in seawater can further alter the color of light perceived in the

water. For instance, clear ocean waters appear deep blue or violet,

whereas coastal waters with large amounts of suspended sediments

or dissolved organic substances causes the reflected light to

shift to longer wavelength colors such as green. In turbid coastal

waters the shift in the wavelength of reflected light is enough to

change the color to yellow.

marine Old Red Sandstone was laterally equivalent to marine

sandstones. The Geological Society of London presented

Sedgwick with its highest prize, the Wollaston Medal, in

1851, and the Royal Society awarded him the Copley Medal

in 1863, for his work on the Silurian System.

Title Post:
Rating: 100% based on 99998 ratings. 99 user reviews.
Author:

Terimakasih sudah berkunjung di blog SELAPUTS, Jika ada kritik dan saran silahkan tinggalkan komentar