                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                              2021 September 15

                        Cyclone Paths on Planet Earth
      Image Credit: National Hurricane Center, NOAA, NASA; Processing:
                          Nilfanion (via Wikipedia)

   Explanation: Where on Earth do cyclones go? Known as hurricanes when in
   the Atlantic Ocean and typhoons when in the Pacific, the featured map
   shows the path of all major storms from 1985 through 2005. The map
   shows graphically that cyclones usually occur over water, which makes
   sense since evaporating warm water gives them energy. The map also
   shows that cyclones never cross -- and rarely approach -- the Earth's
   equator, since the Coriolis effect goes to zero there, and cyclones
   need the Coriolis force to circulate. The Coriolis force also causes
   cyclone paths to arc away from the equator. Although long-term trends
   remain a topic of research, evidence indicates that hurricanes have
   become, on the average, more powerful in the North Atlantic over the
   past 30 years, and their power is projected to keep increasing.

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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.


