The water present at the Earth's surface is explained by the hydrologic cycle concept. Precipitation in the form of rain, snow, or hail is the most important parameter of the hydrologic cycle. In order to evaluate the water budget in a basin that receives water by precipitation, it is necessary to quantify this precipitation. Based on the knowledge of the amount of precipitation, one may estimate how much of this water infiltrated to the soil or was added to the runoff, these parameters being of high importance for designing hydraulic structures. Agricultural activities, too, are planned on the basis of precipitation data. This kind of information is also of great interest nowadays for understanding and predicting the effects of a possible worldwide event, the global heating which directly affects the environment by land degradation and even desertification of very large areas. On the other hand, real-time functioning pluviometers play important roles on the prediction or warning systems for geologic hazards like inundation or avalanches.