Rizhao meter is a professional meteorological instrument used to continuously record the actual "sunshine hours" of a certain place. The core principle is to convert direct solar radiation into measurable physical signals (burn marks or electrical signals) through an optical system, thereby calculating the cumulative duration of solar irradiance ≥ 120 W/m ² in a day. The data is widely used in meteorological observation, agricultural yield estimation, solar energy assessment, tourism climate analysis, and scientific research and teaching. Used for upgrading national benchmark climate stations and regional automatic stations; Real time calculation of PR value and power prediction for photovoltaic power plants; Crop photoperiod research and greenhouse light management; Urban canopy radiation budget and climate change field experiments