The Reason for the Seasons: How the Earth and Sun Interact to Create Seasons
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Explore the Reasons for the Seasons on Earth. When the applet starts up, the approximate location and position of the Earth is shown for the current day and time. Use the Controls (see below) to explore.


  • Map - toggle the map display window on/ may drag this window around as needed. The map shows the day and night regions of the Earth and the background map shows the monthly average incoming shortwave radiation.
  • Top View - changes the viewpoint to be from the "top"
  • Oblique View - changes the viewpoint to be from the "side"
  • Rotation - make the Earth rotate fasster than "real-time" (that is, more than one rotation per 24 hours)
    (Note that when the map is showing, the rotation rate is reduced by a factor of 2.)
  • Orbit - check to have rotation and orbit synchronized
  • Faster Orbit - check to make the orbit faster and not be synchronized to the rotation (to ~14.3 degrees per second, or one complete orbit in about 25 seconds)
  • Solar Insolation Graph - toggle on/off the graph of the Average Daily Solar Insolation at the top of the atmosphere
  • Month slider - as the Earth orbits the Sun, this shows the month during the year; you may also grab the slider thumb to move as desired.
The maps of global images showing solar insulation are 24 year (1984-2007) monthly averages of surface incoming shortwave radiation and were provided by NASA from the GEWEX SRB Shortwave Release 3 algorithm.

The scale for the maps (units are Watts / m2):

Go BACK to Explore the Atmosphere!