Barometer – Pronunciation: [b u rom´ u t u r] – a barometer is an instrument for measuring atmospheric pressure. Temperature, moisture, wind velocity, and barometric pressure are all variables that define weather as the state of atmosphere at a given time and place. The barometer is an instrument for measuring atmospheric pressure, used especially in weather forecasting, pressure falls when it is about to rain and rises when the weather is dry. Because atmospheric pressure changes with distance above or below sea level, a barometer can also be used to measure altitude.

An aneroid barometer indicates pressure on a dial using a needle that is mechanically linked to a partially evacuated chamber, which responds to pressure changes.

The barometer works by balancing the weight of mercury in the glass tube against the atmospheric pressure just like a set of scales. If the weight of mercury is less than the atmospheric pressure, the mercury level in the glass tube rises. If the weight of mercury is more than the atmospheric pressure, the mercury level falls. Please continue to view Cape Watch\’s fine collection of barometers below: