Solar Spectral Distribution and Intensity in the Troposphere

When the radiation from the sun passes through the earth s atmosphere, it is modified both in intensity and 

FIGURE 3.14 Definition of solar zenith angle 8 at a point on the earth s surface. 

To estimate the solar flux available for photochemistry in the troposphere then, one needs to know not only the flux outside the atmosphere but also the extent of light absorption and scattering within the atmosphere. We discuss here the actinic flux F(A) at the earth s surface the effects of elevation and of height above the surface are discussed in Sections C.2.d and C.2.e. 

The reduction in solar intensity due to scattering and absorption can be estimated using a form of the Beer-Lambert law  

The attenuation coefficient, t, represents a combination of light scattering and absorption by gases and 

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