Which of this instrument is used to measure rainfall?
Rain gauge
The rain gauge, also called Ombrometer, is a device used for collecting and measuring rainfall. The thermometer is an instrument that is used to measure temperature. The pycnometer is a standard vessel often provided with a thermometer for measuring and comparing the densities or specific gravities of liquids or solids. Lastly, sphygmomanometer is an instrument that is used for measuring blood pressure.