• MODIS Pic of the Day 15 May 2022

    From Dan Richter@1:317/3 to All on Sun May 15 12:01:24 2022
    May 15, 2022 - "Go!" written by cloud off the coast of Chile

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    In a letter to a friend dated January 14, 1843, Henry David Thoreau
    wrote, “You must not blame me if I do talk to the clouds…”. People have
    long been talking to, gazing at, and imagining seeing things in clouds
    as they look upward from Earth. These days, we can study the clouds by
    looking down on the from space—and the clouds themselves may sometimes
    seem to talk to us.

    On May 6, 2022, a full 179 years after Thoreau admitted to cloud
    conversations, that the Moderate Resolution Imaging Spectroradiometer
    (MODIS) on board NASA’s Aqua satellite acquired a true-color image of a
    remarkable configuration of clouds off the coast of Chile, which seemed
    to be urging “Go!”. Maybe the clouds were sports fans, or—and much more
    likely—cloud and atmospheric conditions created patterns that, when
    combined with human imagination, appeared to create a word in the sky,
    just waiting to be captured by MODIS.

    The Pacific Ocean off the coast of Chile is covered in large banks of
    cloud most of the time, and the region is famous for the formation of
    bizarre patterns. The dark, lacy swirl that forms the “G” is a type of
    open-cell cumulus pattern, while the thick white cloud is basically
    closed-cell marine stratocumulus. The dark breaks in the white cloud
    bank that appear to form the “o” and “!” are simply areas without
    cloud, allowing the dark waters of the ocean to show through and are
    most likely created by wind patterns.

    Back in Thoreau’s day—actually until 1960 when NASA launched the first
    weather satellite—no one had noticed that clouds over the ocean
    frequently appeared to be formed in hexagonal cells with diameters
    ranging from 50 – 100 km (30-60 miles). These cell patterns are created
    by mesoscale cellular convection (MCC). In open cells, air is falling
    in the center of the hexagon and rising around the edges, so clouds
    formed at the edges, creating a lacy-looking pattern. In closed-cell
    clouds, air is rising in the center, so the hexagon is filled with
    fluffy cloud. There is also a third type of cloud formed by mesoscale
    cellular convection—an intermediate type with a radial structure that
    looks something like flowers or a wagon wheel. These are called
    actinoform clouds, derived from the Greek word “aktinos”, meaning
    “ray”. There are at least 2 actinoform clouds within the lacy
    open-celled cloud that makes up the “G”.

    Image Facts
    Satellite: Aqua
    Date Acquired: 5/6/2022
    Resolutions: 1km (2.7 MB), 500m (7.6 MB), 250m (5.4 MB)
    Bands Used: 1,4,3
    Image Credit: MODIS Land Rapid Response Team, NASA GSFC



    https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2022-05-15

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