• ES Picture of the Day 30 2022

    From Black Panther@21:1/186 to All on Tuesday, August 30, 2022 12:00:52
    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.


    Hollow Stems in Amaryllis belladonna

    August 30, 2022

    Menashe_Stems

    Menashe_Stems2

    Photographer: Menashe Davidson menashe.davidson@gmail.com

    Summary Author: Menashe Davidson menashe.davidson@gmail.com

    While in my home-garden (in Rishon LeZion, Israel), I observed the
    erect hollow leafless stems of Amaryllis belladonna plant, also
    known as the Amaryllis lily and the August lily. Carrying
    inflorescences they bear showy funnel-shaped flowers (1st photo). I
    questioned the purpose of why there are hollow stems in some plants.
    Stems of course provide a transport system, mechanical support, and
    a primary growth point for plant. They also improve the presentation of
    the plant’s sexual organs, thereby increasing the plant's chance of
    reproduction.

    The common misconception was to believe that the hollow stem is solely
    for nutrient or water transport. But when I cut the stem in various
    heights, I learned that the hollow stem holds water only in the bottom
    4 or 5 inches (12 cm) -- most of the stem contains air (2nd photo).

    Scientists In University of Guelph (Ontario) studied differences in
    plant stem type, and how effectively they regulate their temperature.
    They found that the stem lumen (hollow portion of the stem) allows the
    plant to maintain a distinct internal microclimate and in the present
    of sunlight, the temperature in the lumen was slightly above that of
    the ambient air. Increases in temperature encourages growth of sexual
    organs in plants, which in turn helps the flower to develop quickly,
    becoming more prominent to pollinators. And this effect is exactly what
    I observed in Amaryllis flowers. (Below)

    Menashe_Stems3


    Rishon LeZion, Israel Coordinates: 31.9730, 34.7925


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  • From Black Panther@21:1/186 to All on Friday, December 30, 2022 11:00:30
    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 Observed from Italian Alps

    December 30, 2022


    Tramonto sull'Aiguille Noire de Peuterey

    Photographer: Valter Luna

    Summary Authors: Valter Luna; Jim Foster

    Shown above is a breathtaking set of crepuscular rays that I
    observed over the Aiguille Noire de Peuterey in the Italian Alps.
    Rays such as this while most often associated with clouds near the
    horizon can also take shape when sunlight filters through mountain
    passes, as was the case on this mid-summer’s evening. However, for
    these rays to be seen, the atmosphere must be dusty. Sunlight
    scattered by dust particles, and or other aerosols suspended in
    the atmosphere, act to project the rays across the sky. Photo taken on
    July 29, 2022.

    Photo details: Nikon D100 camera; Sigma lens 18-250 mm (18 mm); 1/250
    sec exposure; f / 16; ISO 200


    Aiguille Noire de Peuterey, Italy Coordinates: 45.815, 6.893611


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    Atmospheric Effects Links

    * Atmospheric Optics
    * Optic Picture of Day: Gruppo Astrofili Galileo Galilei
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    * 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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