Mie scatter
When Mie scattering or LorenzMie scattering (after the physicists Gustav Mie and Ludvig Lorenz ) is defined as the elastic scattering of electromagnetic waves of spherical objects whose diameter is approximately the wavelength corresponding to the radiation. This scatter can be described physically with the LorenzMie theory .
description
The Mie scattering creates the Tyndall effect . This arises from scattering on objects in which the particle diameter corresponds approximately to the wavelength.
The scattering on the molecules of the air is called Rayleigh scattering, the falling raindrops and floating fog dripping as classic scattering and only the emulsified fat droplets as Mie scattering, although all cases are exactly described by the LorenzMie theory become. In practice, these cases can be easily separated from one another by the different degrees of polarization and the scatter distribution:
Type of dispersion  Dependence on the wavelength 
polarization  Scatter distribution 

Rayleigh  strong  with vertical scattering: linear 
symmetrically forward and backward 
Mie  light  with vertical scattering: light to medium 
slightly asymmetrical to complex 
classic (geometric) on small droplets 
weak  without  mainly forward (visible through the formation of a courtyard ), but also complex (no longer detectable through variation of the droplet size) 
classic (geometric) on large drops 
with transparent material ( Tyndall effect ):  very narrow and weakly forward, so that no halo formation occurs; additionally with transparent material (Tyndall effect): at a large angle 

weak  weak 
Significance in radio technology
Mie scattering is also important in radio technology . In this way, the reflection and the radar crosssection of metallic bodies can be calculated whose circumference is in the order of magnitude of the wavelength of the radio waves. The effective reflective surface of a metal sphere with a diameter of a third of the wavelength is almost four times what would be expected according to classical scattering. Further, smaller maxima occur with integer multiples of the circumference to the wavelength.
literature
 Gustav Mie: Contributions to the optics of cloudy media, especially colloidal metal solutions. Annalen der Physik , Volume 4, Vol. 25, 1908, pp. 377–445, doi: 10.1002 / andp.19083300302 .
 Julius Adams Stratton : Electromagnetic Theory. McGrawHill, New York NY 1941.
 Milton Kerker: The scattering of light and other electromagnetic radiation (= Physical Chemistry. Vol. 16, ISSN 00791881 ). Academic Press, New York NY et al. 1969.
 Hendrik C. van de Hulst : Light scattering by small particles. Unabridged and corrected republication of the work originally published in 1957. Dover, 1981, ISBN 0486642283 .
 Craig F. Bohren, Donald R. Huffman: Absorption and scattering of light by small particles. Wiley, 1983, ISBN 0471293407 .
 Peter W. Barber, Steven C. Hill: Light scattering by particles. Computational Methods (= Advanced Series in Applied Physics. 2). World Scientific, Singapore 1990, ISBN 997150832X .
 Thomas Wriedt: Mie theory 1908, on the mobile phone 2008. Journal of Quantitative Spectroscopy & Radiative Transfer 109, 2008, pp. 1543–1548, doi: 10.1016 / j.jqsrt.2008.01.009 .