2 Responses to “How Does The Angle Of Insulation … Affect The How Much Solar Energy The Earth Absorbs?”

1. bubsir
   February 27th, 2010 @ 11:16 am

   The angle of insolation has several effects on absorption of solar energy.
   * Geometric effect is that a tilted surface spreads the energy over a larger area; such as near the north or south pole where shadows are very long due to the low angle of the sun. This can be worked out precisely in terms of angles using trigonometry
   * Atmospheric path length changes absorption location (more in the atmosphere) so at sunset even an object facing the sun (normal incidence) receives very little energy. This is much more complicated than the geometry effect because it depends on dust and water vapor, clouds or “haze” etc.
   * Reflection changes. This is significant over the oceans where when the sun is low in the sky nearly all light is reflected off the water – Calculations for an ocean with no waves is pretty straight forward, but the real situation is that the sea surface is not flat and the actual effect is difficult to model.
   The other critical factor is albedo or overall reflection of the planet. Here we think of snow, clouds & water vapor, dust, etc. Although many of these are also related to (or effected by) angle, the vary in their own right.

2. Lexico
   February 27th, 2010 @ 2:54 pm

   It’s insolation, not insulation.
   Simply put, the total incident energy is inherently limited by the angle; you only get cos theta times the incoming solar energy as the surface is turned away from the dirction of the sun by theta degrees. Draw a simple diagram to convince yourself.
   For instance, if the solar constant is 1366 watts per square meter, and a solar panel of unit area is skewed by 60 deg, the effective incoming solar power is reduced to 50 % (cos 60 = 1/2) of the solar constant.
   The same principle is the cause of seasonal changes in atmospheric temperature. See a simulation at the link below.http://www.boutichesaid.cv.dz/Earth/Eart…

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