Solar irradiance
OverviewTypesUnitsAt the top of Earth''s atmosphereOn Earth''s surfaceApplicationsSee alsoBibliography
There are several measured types of solar irradiance. • Total solar irradiance (TSI) is a measure of the solar power over all wavelengths per unit area incident on the Earth''s upper atmosphere. It is measured facing (pointing at / parallel to) the incoming sunlight (i.e. the flux through a surface perpendicular to the incoming sunlight; other angles would not be TSI). The solar constant is a convention