MSGID: 1:317/3 63d805e8   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    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.   
      
      
    Anti-twilight Colors and Belt of Venus   
      
      January 30, 2023   
      
       Evolution of Twilight - The Four Bands LD (1)   
      
       Antitiwilight Colors And Belt Of Venus LD caption   
      
      Photographer:  Dario Giannobile   
      Summary Author:  Dario Giannobile   
      
      Shown above are two different portrayals of the  anti-twilight sky   
      and the  Belt of Venus as observed near Syracuse, Sicily, Italy. The   
      image at top was taken on January 4, 2023. In essence, twilight is   
      sunlight scattered by the atmosphere that's still visible when the Sun   
      is below the horizon. Four main visual components of the  anti-dusk   
      have been  identified:   
      • the  blue “upper sky” (US) extending downwards from the observer's   
      zenith   
      • the reddish “Cintura di Venere” (BV)   
      
      • the "blue band" (BB), located below the Belt of Venus and is part of   
      the  shadow of the Earth   
      • the “horizon band” (HB) -- a band of sky between the blue band and   
      the horizon, that although located further into the Earth's shadow, is   
      slightly brighter than the blue band.   
       Color variations in the Anti-twilight sky result from different   
      physical phenomena such as  Rayleigh scattering, molecular   
      absorption, aerosol scattering, multiple scattering and refraction.   
      
      For the bottom image, I used 20 separate shots, taken 2 1/2 minutes   
      apart. To better highlight the color transition, each image was created   
      with the same exposure by setting the camera to  aperture   
      priority mode. Furthermore, a single  white balance was used to   
      highlight the relative variation of the colors of the various portions   
      of the sky at different instants. Although it's not possible to   
      determine with scientific certainty the absolute color captured in each   
      shot, maintaining a constant white balance allows relative color   
      transitions to be highlighted. Distortion in height was employed to   
      show in a single view the different bands that form during sunset.   
      Photos composing this image were taken on November 18, 2022.   
      
      
      Syracuse, Sicily, Italy Coordinates: 37.0755, 15.2866   
      
      
   Related EPODs   
      
       Anti-twilight Colors and Belt of Venus  Splendid Sundog over   
      Montreal, Canada  The Fisherman and the Full Omega Moon  Inferior   
      Mirage off the Coast of Sicily  Crepuscular Rays Observed from   
      Italian Alps  Halo Display Observed from Graubunden, Switzerland   
       More...   
      
   Atmospheric Effects Links   
      
        *  Atmospheric Optics   
        *  Optic Picture of Day: Gruppo Astrofili Galileo Galilei   
        *  Color and Light in Nature   
        *  The Colors of Twillight and Sunset   
        *  Refraction Index   
        *  Image Gallery: Atmospheric Effects   
        *  What is a Rainbow?   
      
   -   
      Earth Science Picture of the Day is a service of the  Universities   
      Space Research Association.   
      
   https://epod.usra.edu   
       
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