Pressure is defined as force per unit area applied to a surface in a direction perpendicular to the surface. Barometric pressure or atmospheric pressure, is the force per unit area exerted on Earth’s surface by the mass of air overlying the surface. High pressure indicates more atmospheric air mass over a given area, whereas, low pressure indicates less atmospheric air mass. Barometric pressure is strongly dependent on elevation, and decreases as elevation increases, due to less overlying air above the surface (shorter column of air) at higher elevations.
Barometric pressure is measured using a barometer. Aneroid (without liquid) barometers are often electronic and typically use capacitive elements to sensor pressure, with the major advantage of capacitive sensing mechanisms being minimal temperature dependence. Capacitive sensing circuits output a voltage that is related to pressure via sensor-specific calibrations. Apogee Instruments Barometric Pressure Sensor is an aneroid barometer consisting of a silicon capacitive sensing element and signal processing circuitry mounted in a compact epoxy plastic/stainless steel housing, and lead wires to connect the sensor to a measurement device.
Typical applications of barometers include barometric pressure measurement in weather networks, often for weather forecasting. Barometric pressure is also measured for evapotranspiration calculations. Additionally, barometric pressure measurements are used to correct the output of sensors that are sensitive to press fluctuations (e.g., Apogee Instruments Oxygen Sensors).