Science

  • Issue 116 / March - April 2017



    Giant Storms: A Mark of Magnificence in the Heavens

    Kadir Firtina

    When taking a quick glance at the planets in our solar
    system you might be surprised to discover what rages beneath seemingly calm surfaces.
    Just as storms happen on Earth, the other planets are also afflicted by storms
    – only these storms are so strong, they can make a hurricane look like a gentle
    rain shower. 

    A tornado that is bigger than the Earth: The Great Red
    Spot

    The storms of a gas giant like Jupiter, a planet 1300 times
    bigger than Earth, are very fierce. Scientists who have studied Jupiter discovered
    that its high rotational rate – a day is only approximately 10 hours – leads to
    the formation of moving gas zones and east-west air jets. The air currents in
    these bands wrap the planet like colorful belts and they move in opposite
    directions at around 600 km per hour. The collision of these horizontal cloud
    bands leads to giant storms.

    The most famous giant storm on Jupiter is the Great Red
    Spot. This giant anticyclone is three times bigger than the Earth. It rotates
    counter-clockwise and has existed for 340 years. Since Jupiter is made only of
    gas, it doesn’t have a physical topography. Therefore, the storm can’t find a
    place to empty its energy. The winds around the Great Red Spot, which looks
    like a red oval eye, have a speed of 400 km per hour.

    It’s still a matter of debate as to how the Great Red Spot reached
    such a giant size.  Scientists have
    argued multiple theories. One theory states that this giant storm has been fed by
    an internal heat energy and engulfs all the other storms it comes across.  As the hot gases that comprise Jupiter's atmosphere rise
    from lower levels to higher levels, eddies form and converge. As cooler
    gas falls back to the planet’s surface, it causes a swirling motion. These
    eddies can last for a long time, because there is no solid surface to
    provide friction. Many adjacent
    eddies are engulfed and merge with the spot, adding to the energy of the storm
    and contributing to its longevity.

    Other scientists mention that the Great Red Spot has begun
    to shrink. While the spot was about 41,000 km wide in the 1800s, it had shrunk
    to 23,300 km in 1979, according to the measurements of Voyager 1 and 2. Recent
    Hubble telescope measurements report the storm’s size as 16,500 km wide.  Another large storm, whose diameter is as
    large as the Earth’s, was observed below the Great Red Spot.

    Winds twice as fast as sound

    During hurricanes and tornadoes, the winds on Earth are
    strong enough to demolish buildings. Yet if we spent a day on Neptune, where
    the fastest winds in the solar system occur, we wouldn’t be so impressed with
    the Earth’s winds. Winds on Neptune can reach speeds of 2400 km per hour. This
    is twice as fast as the speed of sound (1235.5 km per hour).

    Astronomers think that freezing weather conditions may lead
    to the strong winds on Neptune.  As on
    Jupiter, there is no friction to slow the currents down – though here the
    culprit is an icy planet, not a gaseous one. The fastest jet streams are
    visible as dark spots. The most important ones were the Great Dark Spot,
    located in the southern hemisphere, and the Small Dark Spot, which was south of
    the great dark spot.

    The Great Dark Spot was an anticyclonic storm and was first
    discovered by Voyager 2 in 1989.  It was
    about the same size as Earth, and was very cold and dark. There were silky
    cirrus clouds around the spot made up of crystals of frozen methane.
    However, the Great Dark Spot was not observed by the Hubble Space Telescope in
    1994.

    The Small Dark Spot, also called The Wizard’s Eye, was a
    southern cyclonic storm. It was also observed by Voyager 2. But again, when
    the Hubble observed Neptune in 1994, the storm had disappeared.

    In lieu of these two storms, a new dark spot was discovered
    in the northern hemisphere. This storm, whose width is almost 2400 km, is still
    active. Apart from this storm, there are also speedy and comparatively small
    clouds called “scooters.”

    When observed at a distance, Saturn and its giant rings seem
    quite taciturn. However, beneath the surface are rough storms like the Great White
    Spot, discovered in 1990, and the Giant Storm, discovered in 2010. Although
    cloud zones that are parallel to the equator are observed in Saturn’s atmosphere,
    the color and contrast between the bands are not as striking as on, say,
    Jupiter. In these neighboring zones the clouds move in opposite directions at
    enormous speed. White spots are observed when some of them interact, creating
    storms that can reach a truly gigantic size.

    These storms can reach speeds of 1800 km per hour, making
    them the second fastest storms in the solar system after Neptune’s. The most
    striking storms on Saturn are those observed above the North Pole. These storms
    have an unusual hexagonal shape, which is due to atmospheric vortices in the
    polar regions. The biggest of these storms has a width of about 13,800 km. Once
    again, the existence of these huge storms was proved by Voyager 1 and Voyager 2
    in 1980 and 1981.

    In 2009, the Giant Storm was observed more closely thanks to
    NASA’s Cassini Spacecraft. As a result of these observations, it has been
    revealed that the Giant Storm has existed for 30 years and has winds estimated at
    480 km/ph.

    When we look at other planets in the solar system, Venus has
    dramatic differences between high and low pressure in its atmosphere. The
    planet is covered by thick, heavy clouds made of sulfuric acid. Venus is made
    of active volcanoes, which produce toxic gases and constant heat; the planet is
    literally shaped by toxic smoke.

    Mars is famous for giant red dust storms that blanket the
    entire planet and last for months. When Mariner 9 arrived on Mars in 1971, it
    found out that the atmosphere was thick with "a
    planet-wide robe of dust.” The only visible object was Mount
    Olympus Mons, which is nearly three times taller than Mount Everest.




















































    Upon observing the atmospheres of nearby planets, and the enormous
    storms that torment them, it’s hard not to contemplate the enormous power that
    exists in the universe – and we find ourselves grateful that Earth was created
    in such a temperate manner. Without such an amenable climate, life wouldn’t be
    possible.
        

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