为了提高非理想条件下气象能见度的观测精度，从大气光传输理论出发，提出了等效视感阈值和广义科西米德定律，建立了非理想条件下气象能见度观测的相对误差和修正系数计算公式，并模拟分析了非黑色目标在非水平天空背景条件下的气象能见度观测的相对误差和修正系数。结果表明：修正系数受目标反射率、背景反射率、目标与背景距离以及大气消光系数的共同影响，并呈现一定的规律性分布。为了满足观测业务的需求，非理想条件下气象能见度的观测结果需要修正，特别是当修正系数小于0.8时。

In order to improve observation precision of the meteorological visibility under non-ideal conditions, the equivalent visual threshold and general Koschmieder′s law are put forward and demonstrated based on the atmospheric optical transmission theory. Under the non-ideal condition, the observation visibility formulas of relative error and the correction coefficient are established. The weather visibility relative error and the correction coefficient of the non-black targets are analyzed under the conditions of non-parallel level of the sky background. Results show that the correction coefficient of visibility observation is influenced by target reflectivity, background reflectivity, the distance between target and background and atmospheric extinction coefficient, and the distribution of correction coefficient has a certain regularity. In order to meet the needs of visibility observation business, the results of visibility observation under non-ideal conditions need to be modified, especially when the correction coefficient is less than 0.8.