the fraction of radiant energy that is reflected from a surface
同义词：coefficient of reflection, reflection factor, reflectivity
reflectance详细解释
re.flec.tance
n.（名词） The ratio of the total amount of radiation, as of light, reflected by a surface to the total amount of radiation incident on the surface. 反射比：被表面反射的辐射（如光）总量与入射到表面上的辐射总量之比
