RADIATION COMPONENTS OVER BARE AND PLANTED SOILS IN A GREENHOUSE

The radiation components that comprise net total radiation, incoming and outgoing solar and longwave radiation were measured over bare and planted soils in a greenhouse at the Solar Energy Research Center, Baghdad, Iraq. Crop albedo values were calculated and net radiation related to solar radiation by regression analysis. This paper shows that the crop albedo was close to 0.25 when the greenhouse floor was completely covered. The crop reflection coefficient decreased markedly with higher solar elevation. Heating coefficient values were consistently positive and ranged between 0.18 and 0.41 during the growing season. The net radiation was strongly correlated to the incoming solar radiation inside the greenhouse. Incorporating albedo in the linear relationship between net and net shortwave radiation was unnecessary. © 1990.