Photosynthetically active radiation loss in the atmosphere in North China

Based on an understanding of energy, empirical formulas of hourly PAR (photosynthetically active radiation) under all sky conditions in North China were introduced and applied. An interesting and important phenomenon of the absorption of “water vapor factor” in 400–700 nm was studied and its real mechanism can be explained by the energy consumption of the substances (gas, liquid, solid–phase) through OH radicals during chemical and photochemical reactions. The PAR at the top of the atmosphere was estimated with good agreement. PAR losses in the atmosphere associated with “photochemical factor” and other materials in North China are spatial and seasonal dependence; their “annual” averages were 15.33 and 309.30 W m–2 in North China, respectively. The energy loss related to the “photochemical factor” should be considered in all kinds of basic processes in the atmosphere and model studies, including radiation transmission, photochemistry, air motion, and climate.