a barometer calculates changes in air pressure. so if it has a rapid change, im guessing it has just been a "rapid" change in air pressure
A barometer is used to measure air pressure. A Mercury Barometer uses a column of liquid mercury supported by air pressure. The length of this liquid column gives a measure of the air pressure. Air...
It's a useful instrument for detecting weather. It measures air pressure.
A barometer is an instrument used to measure the weight of the air pressing down on the earth's surface which is known as air pressure.
They both measure air pressure, but in different ways