• ES Picture of the Day 30 2023

    From Black Panther@21:1/186 to All on Mon Jan 30 11:01:12 2023
    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
    • 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

    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.


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