Particles and water vapor as absorbers of solar radiation

Measurements of the absorption of solar radiation within the atmosphere are rare, mostly because the common 'divergence method' for absorption measurements involves great instrumental problems, requires aircraft measurements at different heights, and is applicable only to horizontally homogeneous atmosphere-ground systems. To overcome this situation a new method was developed to obtain the absorption of solar radiation in situ and in horizontally inhomogeneous environments. The new method requires the determination of the mean absorption coefficient of the absorber of interest in the solar spectral region and the solar radiation supply, i. e. the integral of the radiance of the total solar radiation flowing from all directions to the location of measurement. The product of these two properties gives the solar volume absorption rate, i. e. the energy of solar radiation absorbed per unit time interval and per unit volume by the absorber of interest.