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“diffuse irradiance”
diffuse radiation (s) (noun), diffuse insolation, diffuse irradiance, diffuse illuminance, diffuse sunlight
All of these terms are descriptions of solar radiation that is received indirectly on the surface of the earth, rather than directly from solar rays: "Diffuse radiation, etc. are all caused by the scattering that is a result of clouds, fog, haze, dust, or other barriers in the atmosphere."
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fus-, fun-, fund-, fut-, found-
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