• ES Picture of the Day 20 2020

    From Black Panther@21:1/186 to All on Fri Nov 20 11:00:46 2020
    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.


    Cibiana di Cadore and Circumzenithal Arc

    November 20, 2020

    6a0105371bb32c970b026bdea4f93d200c

    Photographer: Marcella Giulia Pace
    Summary Authors: Marcella Giulia Pace, Jim Foster

    Shown above is a cheery circumzenithal arc (CZA) as observed from
    the clock tower in Cibiana di Cadore, Italy, a municipality in the
    Alps of northeastern Italy. These colorful arcs result when
    sunlight is refracted by similarly oriented, hexagonal ice
    crystals in the atmosphere. Sunlight passes through a crystal’s upper
    basal face and then exits through one of its side faces. However,
    they only appear when the Sun is positioned lower than 32 degrees
    above the horizon. Photo taken on August 11, 2015.

    Photo Details: Canon Powershot sx50hs camera; 1/500 sec. exposure;
    f/5,6; ISO 80.
    * Cibiana di Cadore, Italy Coordinates: 46.38452, 12.28604

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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?

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

    https://epod.usra.edu

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  • From Black Panther@21:1/186 to All on Sun Dec 20 11:00:38 2020
    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.


    Archive - Blue Light From Deep Snow

    December 19, 2020

    Bluesnow

    Every weekend we present a notable item from our archives. This EPOD
    was originally published December 22, 2003.

    Provided by: Cindy Foster
    Summary authors & editors: Jim Foster

    After a big snowstorm, when you're shoveling your walkway or just
    measuring how much snow fell, have you ever noticed a turquoise or
    robin egg blue color? The color isn't due to blue snowflakes nor is it
    a result of the same process responsible for making the sky look blue.
    Rather it results from the optics of large, non-spherical particles. If
    new-fallen snow is more than about 10 inches (25 cm) deep, the myriad
    snow crystals both scatter and absorb sunlight (even on an overcast
    day). The longer wavelengths (red and yellow) of visible light are more
    readily absorbed than are the shorter wavelengths (greens and blues).
    Eventually, the red light is completely absorbed, and only blue light
    emerges when a hole is poked into the snow. If the hole is deep enough,
    the blue color completely disappears since all of the light will be
    absorbed.

    The photo above was taken last February in Silver Spring, Maryland the
    day after a powerful nor'easter buried portions of the Middle Atlantic
    region and New England under nearly 2 feet (60 cm) of snow. Anytime
    this thick mantle of snow was jabbed with a yardstick, blue light was
    liberated. Here's hoping that you have a nice Christmas and that no
    blue snowflakes start falling or blue memories come calling.


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    Cryosphere Links

    * Guide to Frost
    * What is the Cryosphere?
    * Bentley Snow Crystals
    * Glaciers of the World
    * Ice, Snow, and Glaciers: The Water Cycle
    * The National Snow and Ice Data Center Google Earth Images
    * Snow and Ice Crystals

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

    https://epod.usra.edu

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    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (21:1/186)