Subj : ES Picture of the Day 30  2023
To   : All
From : Dan Richter
Date : Mon Jan 30 2023 11:01:12

 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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