Fog specification device, fog specification method, and fog specification program

According to the present invention, a point data acquisition part (21) acquires a set of point data that indicate reflection points and have been obtained by a light sensor (41) that receives reflected light that is the result of radiated light beams being reflected at the reflection points. The point data are combinations of primary point data that indicates a primary reflection point that is a reflection point for a particular beam of light and secondary point data that indicates a secondary reflection point that is a reflection point for the particular beam of light and from which the intensity of reflected light is lower than from the primary reflection point. A fog specification part (22) specifies the thickness of fog on the basis of the distribution of the distances between the primary reflection points and the secondary reflection points of the point data included in the acquired set. 点数据取得部(21)取得由光传感器(41)得到的表示反射点的点数据的集合，该光传感器(41)接收放射出的光束由反射点反射后的反射光。点数据是1次点数据和2次点数据的组，该1次点数据表示针对某个光束的反射点即1次反射点，该2次点数据表示针