 EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes
and phenomena which shape our planet and our lives. EPOD will collect and
archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


 Crepuscular Rays over the Roof Tops of Manchester

   December 17, 2020

    Crepuscular rays sept 2020
   Photographer:  Rob Lawley
   Summary Author:  Rob Lawley
   As shown above,  rays of light from the setting  Sun rise up
   above roof tops in Manchester, England. Gaps in the clouds in the
   western sky confine the rays to bands in a fan-like form. In this image
    dust, smoke and other dry particles in the atmosphere more
   effectively  scatter blue and green light (shorter  wavelengths)
   allowing more yellow and red light (longer wavelength) to pass through.
   The dusty atmosphere acts to make the rays easier to detect. Light from
   the setting Sun has to pass through up to 40 times as much air as light
   from an overhead Sun. This effect is known as  Rayleigh scattering,
   named after the nineteenth-century physicist  Lord Rayleigh.

   Whilst the bands appear to radiate from a point behind the roof, this
   is nothing more than an optical illusion. The Sun is about 93.6 million
    miles from Manchester, so the bands are near parallel. The fan-like
   form results from the observer’s  perspective, in much the same way
   as railway lines appear to merge to a single point in the distance.

   At the time the image was made the Sun was still above the horizon, so
   technically the bands are not  crepuscular rays (from Latin
   crespuculum which means twilight or after sunset). Photo taken on
   September 4, 2020, at 7.29 p.m.
     * Manchester, U.K. Coordinates:  53.4808, -2.2426

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Atmospheric Effects Links

     *  Atmospheric Optics
     *  Color and Light in Nature
     *  The Colors of Twillight and Sunset
     *  Refraction Index
     *  Image Gallery: Atmospheric Effects
     *  What is a Rainbow?

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   Earth Science Picture of the Day is a service of the  Universities
   Space Research Association.

https://epod.usra.edu
 
