Short Wave Radiation on Inclined Surfaces in Model Plant Communities
1969
Anderson, Margaret C. | Denmead, O.T.
The paper describes methods for easy calculation of the flux densities of direct and diffuse radiation on inclined foliage in model plant stands. The stands are composed of randomly oriented, constantly inclined, flat foliage surfaces. The calculations require knowledge of the flux densities of direct and diffuse radiation on a horizontal surface above the stand, foliage inclination, foliage area index, and solar altitude. For direct radiation, the effects of changes in foliage inclination angle on the average radiation receipt by the foliage depend strongly on solar altitude and on season and time of day. Relatively large differences can exist between stands of different foliage inclination. The distributions throughout the day of direct radiation on inclined foliage surfaces in the stand are shown to be quite different from those on horizontal surfaces. There are only small differences between surfaces of different inclination in the receipt of diffuse radiation, particularly at the top of the stand. Trial calculations suggest that in the agricultural growing seasons of many temperate regions the daily receipt of direct radiation by the foliage of a stand per unit of ground surface will increase with foliage inclination. Some problems of modelling energy-dependent plant processes in stands are discussed.
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