Does a Barometer Measure Relative Humidity?

Barometers were first produced in the mid 19th century.

A barometer measures atmospheric air pressure and can provide a good indication of short-term weather trends. It does not, however, measure humidity. A hygrometer is used to measure humidity, which relates to the amount of moisture in the air for a given temperature.

Function

According to the BBC Weather Centre the gases in the earth's atmosphere have weight and therefore exert a pressure on their surroundings. A barometer's basic function is to keep track of those pressures.

Measuring Humidity

A common type of hygrometer is a psychrometer, which uses the evaporative cooling of a thermometer bulb to measure humidity according to physics.kenyon.edu.

Calculating Relative Humidity

Relative humidity can be calculated by dividing the actual vapor density of the air by the saturation vapor density and multiplying by 100, according to hyperphysics.phy-astr.gsu.edu. A value of 100 percent equates to the maximum moisture content of the air at any given temperature.

References

• The BBC Weather Centre: What is Humidity?
• The BBC Weather Centre: Barometers
• Hyperphysics.phy-astr.gsu.edu: Relative Humidity
• physics.kenyon.ed: Hygrometers