Home > Animations > Daylight Hours, Timeline

Daylight Hours, Timeline

Daylight Hours Animation with Google Earth

This Google Earth time animation is a simplified visualization of the how number of daylight hours (insolation duration) varies according to latitude over one year.

Each 5-day step of the animation displays a series of coloured bands. Boundaries between these bands are isochrones, representing whole numbers of daylight hours,  0 – 24.  The Black and Yellow regions at the poles correspond to perpetual night and daylight. 

Calculations are approximate, and decrease in accuracy away from the Equator and Prime Meridian.  For comparison I recommend checking out the tables on the U.S. Naval Observatory website.

Daylight Hours Timeline

  • To view the timeline, simply download the file and hit play
  • Transparency may be altered by highlighting the Overlays folder,  and using the transparency slider.

At faster speeds, on looped playback, the effect of the animation is quite hypnotic. Might not be a good idea to stare at it for too long. 😉 

Basic outline of how the file was created:

– I generated the KML with a Perl script. Iterating Sunset and Sunrise time functions to find latitudes for integer hour values.  

– The 26 bands displayed in each time span are a contiguous series of single colour, image overlays.  

– Every overlay uses the same, 2×2 pixel jpeg, stretched around 360 degrees longitude.  KML’s <color> tag assigns the colour.

  1. Dr Geoff Camplin
    April 3rd, 2008 at 18:27 | #1

    Many thanks for this program. I am planning a holiday around the world going from Northern hemisphere to Southern hemisphere and back again from east to West. The information was very valuable in understanding how the sunrise and sunset changes in each location.

  2. Drew
    December 3rd, 2009 at 19:02 | #2

    Is there a way to get output from this animation such as total daylight hours for a given region for the year? Please advise

  1. No trackbacks yet.