The process whereby light or other types of radiation are
absorbed and reemitted in all directions, with essentially no change in
wavelength (or energy). Different types
of scattering involve different types of particle.
|Scattering is the process by which visible light
entering Earth's atmosphere is diffused by the gases and dust in the
air. The shorter wavelength, higher frequency light at the blue end
of the visible spectrum (1) is scattered more by particles in the
atmosphere (2) than the red end end of the spectrum (3), because the
average size of the particles in the air corresponds with the blue
light's wavelength. This diffusion is the reason why the daylight
sky appears blue (4) and sunlight is perceived as having a yellow
cast. When the Sun is at a low level in the sky at dawn or sunset
the light has to pass through a greater thickness of atmosphere, so
that only light from the red end of the spectrum reaches the surface
in any quantity – hence red skies at sunset or sunrise.
Photons scatter off electrons
by Thomson scattering or, if
the photon has a lot of energy (as in the case of X-rays
and gamma-rays), by Compton
scattering. If the scattering particle is small compared with the wavelength,
the photon experiences Rayleigh
scattering; if it's large, the process is known as Mie
Elementary particles can be scattered by atomic nuclei or other particles.
It is the means by which the structure of atoms
was first discovered. See Rutherford's
experiment and atomic model. Most knowledge of elementary particles
and the discovery of new ones has been obtained by scattering experiments
in particle accelerators.
AND OPTICAL PHENOMENA