Which instrument is used to measure liquid precipitation over a specific period of time?

A rain gauge is the instrument specifically designed to measure the amount of liquid precipitation over a designated time period. It typically consists of a cylindrical container with a funnel that collects rainwater. The collected water is measured in millimeters or inches to quantify how much precipitation has fallen. This measurement is crucial for meteorological research, weather forecasting, and hydrology, as it provides valuable information about rainfall patterns and water availability.

In contrast, a thermometer measures temperature, allowing for assessments of heat and cold rather than moisture levels. A barometer detects atmospheric pressure, which helps to predict weather changes but does not provide information about precipitation. An anemometer measures wind speed, which is unrelated to the levels of liquid precipitation. Each of these instruments serves a unique purpose within the field of meteorology, but only the rain gauge focuses on quantifying precipitation.