1. A self-registering rain gauge: Because little Timmy was so interested in measuring things and keeping the data, his parents gave him a pluviograph, not only to keep track of how much it rained during the day, but also to save the information over a period of time.
2. A branch of meteorology dealing with the automatic registration of the precipitation of rain, snow, etc.: The official weather reporters for radio and TV stations; as well as, for newspapers, rely on pluviographs for their information and weather forecasts in order to tell and to show the viewers if there will be downpours or just drizzles on specific days.