# What instrument is used to measure air pressure?

A barometer

#### Spiegazione:

A barometer using mercury is common. The pressione atmosferica presses down on a reservoir of mercury and the mercury is forced up the tube a certain distance depending on the pressure. This is often recorded as "mm" Hg or (rarely) "inches" "Hg".

Our lab uses meters with a digital display to measure the pressure and I suspect that they use a method similar to an aneroid barometer which uses wafers that expand and contract with pressure changes to move an instrument. More can be read here: http://www.windows2universe.org/earth/Atmosphere/measuring_press.html