Cloud fraction is the percentage of each pixel in satellite imagery or each grid box in a weather or climate model that is covered with clouds. A cloud fraction of one means the pixel is completely covered with clouds, while a cloud fraction of zero represents a totally cloud free pixel.Cloud Fraction NASA Earth Observatory, January 2005. Cloud fraction is important for the modeling of downward radiation.L. Chen, G. Yan, T. Wang, H. Ren, J. Calbó, J. Zhao, R. McKenzie (2012), Estimation of surface shortwave radiation components under all sky conditions: Modeling and sensitivity analysis, Remote Sensing of Environment, 123: 457–469. Unlike sky cover, cloud fraction is often treated as the proportion of a horizontal area covered by clouds as viewed from below.
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