All surfaces are rough; the roughness of the surface is related to the wavelength of the light ray. As the surface having more roughness absorbs more energy from the light ray and will scatter it in different directions depending on the wavelength of the light ray. The rough surface of a car or pieces of jewellery can be taken as a good example of scattering through a rough surface.
This type of scattering through impurities present in the volume helps in the medical types of equipment. Thompson mechanism, which is also known as elastic scattering, is a good example of this type of scattering which is used in medical X-ray photographs.
This type of scattering occurs where light is scattered by charged particles by levelling the energy of the incident radiation and the rest energy of the charged particle present. The passing of light ray through any liquid in which light beam scatters only with the tiny fat droplets is a good example of this type of scattering. The sunlight travels a longer distance through the atmosphere.
Scattering blue light is more than red light. As a result, more red lights reach our eye than the blue light. Hence sunrise and sunset appear reddish.
These particles scatter all colours of incident white light from sun to the same extent and hence when the scattered light reaches our eyes, the clouds are seen white.
It was first explained by John Tyndall in Scattering of Light by small particles and molecules in the atmosphere Different from reflection, where radiation is deflected in one direction, some particles and molecules found in the atmosphere have the ability to scatter solar radiation in all directions.
Selective scattering or Rayleigh scattering occurs when certain particles are more effective at scattering a particular wavelength of light. Air molecules, like oxygen and nitrogen for example, are small in size and thus more effective at scattering shorter wavelengths of light blue and violet.
The thin yellow line is the transmittance of a yellow filter slightly idealized , and the green line is obtained by applying the filter to the spectral distribution given by the blue line.
The colour without and with the yellow layer is also shown. Autumn leaves and blue, cloudless sky. Automatic white balance. Immediate comparison looking alternatingly out of the window and at the screen attests optimal reproduction of the colours. The same autumn leaves one day later with overcast sky and drizzle. Here now, the right picture is closer to the visual impression. This could hardly have been decided without immediate comparison. Dietrich Zawischa Contact Deutsche Version. In the air, part of the sunlight is scattered.
The small particles molecules, tiny water droplets and dust particles scatter photons the more, the shorter their wavelength is. Therefore, in the scattered light, the short wavelengths predominate, the sky appears blue, while direct sunlight is somewhat yellowish, or even reddish when the sun is very low.
The colours of sunrise and sunset sometimes even show themselves on the moon. When during a lunar eclipse the earth shades the moon, some light is scattered into the shadow region by the earth's atmosphere. This light is reddish, as shorter wavelength light is largely scattered to other directions. As viewed from the moon, the earth's atmosphere would be seen as a shining border, red at the inner side if there are no clouds, and becoming pale and bluish outwards.
Next we consider a small droplet which consists of N molecules of water and is assumed to be very small compared to the wavelengths of visible light.
To simplify things, we assume that each of the molecules feels the field of the incident wave. In this crude approximation, the whole droplet behaves like a single molecule with an N -times larger polarizability, and the scattered wave has N 2 - times the intensity than that of a single molecule. As long as the droplet is small compared to the wavelengths, the short waves are scattered more than the longer ones. Larger droplets With increasing droplet size the situation changes: the scattered waves coming from different parts of the drop interfere and partially extinguish each other.
For large drops, the scattered waves coming from inside cancel each other, and what remains is interpreted as reflected and refracted waves. In this case we speak of Mie scattering the spectral composition of the scattered light depends on the scattering angle. In dense clouds, this dependence is averaged out by varying drop sizes and multiple scattering and the clouds appear white or grey.
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