|MadSci Network: Earth Sciences|
Given the distribution of land area, you could expect the amount of land area covered in sunlight to vary throughout the day. If you were to plot the area of land lit, the result will be sinusoidal-like with two or more highs and a like number of lows.
You might best estimate the amount of land area lit by sunlight by looking at a globe of the earth, initially positioned so that you can see the approximate location of the prime meridian (passes through Greenwich, England) centered on the globe. Then estimate the percentage of the globe that you perceive as land area, remembering that the Sun's 'view' of Earth is similar. Repeat your estimation process, advancing the globe 15 degrees of longitude East of the prime meridian for each estimate. Advancing by 15 degree increments will give you 24 measurements, comparable to the 24 hours in a day.
The following website provides a two-dimensional projection of the Earth and shows time-zones. This map could also be used to estimate land area lit by sunlight though the land mass distortion near the poles may be a problem. Note from this reference that Zulu time is associated with one of the time zones, so that it would be better to associate your estimates with longitude at the center of the globe as viewed from the Sun instead of Zulu time.
reference: http://www.flybyweb.com/ zulu.htm
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