Solar Energy Animation

Movie Animation Controls


This animation demonstrates how the intensity of the energy reaching Earth's atmosphere from the sun varies with location and time. Both intensity and declination (latitude of Earth which is closest to the sun) vary through the months.The intensity of solar radiation is called insolation. Insolation makes Earth habitable and it drives our weather. It measures energy received per area during a specific time interval. In this case the colored maps show Joules per square meter per day. By matching the map color to the scale at the bottom of the map, you can learn the insolation value at a specific location and on a specific date.

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First select the "Animation Time Period" which specifies a range of dates for the solar energy animation. Next select "Earth's Declination" which determines whether or not solar declination should be fixed at zero degrees (at the equator) or vary as it does in reality (maximum: 23.5 degrees). The two declination options are provided to answer the question: What causes Earth's seasons? To step through the days of the year in your time period, then use the "Movie Animation Controls".


Animation Time Period

Select a month, season or entire year of data.

Earth's Declination

Enable or disable variations in the sun's declination as it varies through the year. Declination represents the latitude which is closest to the sun and thusly gets the greatest intensity of energy. Disable this (0) to see if energy intensity still varies through the year as a function of the Earth's distance from the sun.


Start, Pause, Restart

These controls start and stop the animation. Starting the animation will display changes in energy intensity as they vary by day of the year.

PopUp Image

This button will open a new window with the current energy intensity display.

Back, Next

Display the next or previous day's energy intensity values.

Slower, Faster

Slow down or speed up the animation.

Questions to Answer

  • Set the Earth declination to 23.5 degrees:
    • For today's date, find the insolation value in the middle of: United States, Europe, Brazil, India, China, and Australia.
    • Pick a location and find out which month and season has the greatest change in insolation.
    • At the same location, whick month and season has the least change of insolation?
    • On what dates is the insolation symmetric (the same) above and below the equator?
    • What are the seasons for summer and winter in the Southern Hemisphere?
  • Set the Earth declination to zero:
    • Pick a location and find out how much insolation changes due to the changing distance from the Sun.


The data used for creating the images in this viewer were made using formulas adapted from Physics of Climate, J. P. Peixoto, A. H. Oort, American Institude of Physics 1992.

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