Abstract: Weather phenomenon recognition is of great significance for transportation, agriculture and human daily activities, and automatic weather observation technology based on optical principle has broad application prospects. At present, the distinction of fog and haze by the existing meteorological instruments is mainly based on visibility range, with a single judgment condition, and to identify rain and snow, precipitation sensors are required, which is technically complex. In this work, based on the differences in scattering characteristics of rain, snow, fog and haze particles from different angles, a universal weather phenomenon recognition system based on forward and backward scattering principle is designed and developed, which identifies fog, haze, rain, snow and clean days through two-way scattering angle signals of 40° and 120°. Observation experiments in relatively stable environments show that, the system can realize accurate measurement of atmospheric visibility within a range of 60 m–13 km, and the correlation coefficient between the observed visibility results and the standard visibility below 5 km can reach 0.98. Moreover, it is shown that the range of the measured light intensity ratios in fog, haze, rain, snow and clean days are 0.16–0.19, 0.21–0.45, 0.11–0.15, 0.75–0.90 and 0.47–0.58, respectively, which can realize accurate differentiation of different weather types.

Key words: forward scattering, backward scattering, visibility, scattering light intensity ratio, weather phenomenon