Q:

What is the instrument used to measure air pressure?

A:

Quick Answer

A barometer is the scientific instrument used by meteorologists to measure atmospheric pressure. There are three main types of barometers: mercury, aneroid and digital barometers.

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A basic mercury barometer consists of a single open-ended glass tube and a reservoir. The glass tube is filled with mercury and is placed upside down in the reservoir, which also has mercury in it. The mercury level in the tube drops, creating a vacuum at the top. The barometer functions by balancing the weight exerted by the atmospheric pressure against the weight of the mercury in the glass tube. An aneroid barometer typically has a sealed metal chamber that contracts and expands based on the surrounding atmospheric pressure. A mechanical tool is used to measure how much the chamber contracts or expands. Digital barometers use electrical charges to accurately measure and display complicated atmospheric data.

A change in atmospheric pressure directly affects the weather. Meteorologists use barometers to forecast short-term weather changes. Atmospheric pressure that rises slowly, over a week, is usually an indication of settled weather that will likely last for a long time. An unexpected drop in atmospheric pressure within a few hours typically indicates an approaching storm, which will likely last a short period of time, accompanied by strong winds and heavy rain.

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Related Questions

  • Q:

    What tool measures air pressure?

    A:

    The barometer is a tool that measures air pressure. Barometers are calibrated for a specific unit, that displays the current air pressure of the environment that the tool is exposed to.

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  • Q:

    What is the air pressure in the exosphere?

    A:

    The air pressure in the exosphere is extremely low due to its high altitude and the distance between the molecules it contains. The exosphere is the Earth's uppermost atmospheric layer, and it is not highly affected by the Earth's gravitational pull.

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  • Q:

    What happens to air pressure as altitude increases?

    A:

    As altitude increases, the air pressure decreases. The surface of the earth is the bottom of an ocean of air. The layers on top increase pressure so that at sea level a body is under 14.7 pounds of pressure per square inch. Moving up in altitude decreases weight of air that causes the pressure. At 18,000 feet, the pressure decreases to 7.4 pounds of pressure per square inch.

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  • Q:

    Why is air pressure different in the different layers of the atmosphere?

    A:

    According to Climate Education for K-12 from North Carolina State University, air pressure decreases as elevation increases in higher levels of the atmosphere. The atmosphere has four levels. From the closest level to the surface of the earth to the highest level, they are as follows: the troposphere, the stratosphere (where the ozone layer lies), the mesosphere and the thermosphere.

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