What does a barometer really measure?

Question

What does a barometer really measure?

Answer 1

A barometer is an instrument used to measure atmospheric pressure. It can measure the pressure exerted by the atmosphere by using water, air, or mercury.

Answer 2

changes in air pressure

Answer 3

it measures the presure of the atmosphere in milibars and other units

Answer 4

Air pressure

Answer 5

atmospheric pressure

Answer 6

The barometer measures the atmospheric pressure, which is on average 29.9 inches of Mercury, or 1013.25 millibars, today called hectoPascals. It correspond to about one kilo pressure per square centimeter.

The barometer can show you if you are in a high or low pressure. The latter is always associated with wind and rain. Low pressures are places where the air is rapidly rising, causing wind as pressures tend to fill up, and rain as the rising air cools down and condensate, forming clouds and eventually rain.

High pressure, on the other hand, are regions where the air sinks thus dissolving clouds as they warm up. The sky is then usually clear and sunny with only a possibility of fog early in the morning.

Watching a barometer every day is a great way to follow with the weather. A barograph is a recording barometer. You can then watch how fast the pressure rises or drop. A seafarer's rule of thumb is that a fall or rise of ten millibars within eight hours is a sure sign that gale winds can be expected.