Q:

How do mercury barometers work?

A:

Quick Answer

A mercury barometer balances the weight of mercury in a glass tube against the atmospheric pressure above a reservoir of mercury at its base to provide a measurement of atmospheric pressure. This weather instrument works like a set of scales to forecast the weather.

Know More

Full Answer

A classic mercury barometer is constructed from a 3-foot glass tube that is open at one end and sealed at the opposite end. The glass tube is filled with liquid mercury and rests upside-down in a reservoir of mercury. As the mercury moves down the glass tube, a vacuum is created. When the atmospheric pressure above the reservoir increases, the mercury inside the tube rises. As atmospheric pressure decreases the mercury moves down the tube, into the reservoir. This type of barometer was first constructed in 1643 by Evangelista Torricelli.

The change in the mercury level in the glass tube is equal to the pressure exerted by the air above the reservoir and is measured using the scale marked on the glass tube. Changes in atmospheric pressure occur prior to weather changes. Sudden drops in atmospheric pressure indicate stormy weather, while sudden rises in pressure predicate brief periods of fair weather. Gradual increases and decreases in atmospheric pressure point to a more sustained weather pattern.

Learn more about Physics

Related Questions

  • Q:

    How does a fulcrum work?

    A:

    A fulcrum is the fixed support or pivot point for a lever, which is a simple machine used to overcome resistance. The lever is a stiff rod or bar, and the location of the fulcrum determines the class of the lever. Levers are useful to increase force, increase speed or change direction of a force, according to HowStuffWorks.

    Full Answer >
    Filed Under:
  • Q:

    How do engines work?

    A:

    An engine works by converting force into mechanical work. Internal-combustion engines use fuel to create heat. The heat expands the gas in a piston, creating the force to move the piston, causing the crankshaft to turn and provide power to propel an automobile down the road.

    Full Answer >
    Filed Under:
  • Q:

    How does Moore's law work?

    A:

    Moore's law is an empirical law, meaning that it was derived from observation rather than from general principle and therefore doesn't seem to be driven by a single underlying force. According to Mooreslaw.org, the law was first articulated by Intel co-founder Gordon Moore and states that the number of processing elements that can be fitted onto a chip at a given cost roughly doubles every year.

    Full Answer >
    Filed Under:
  • Q:

    Do binaural beats really work?

    A:

    In 2014, the effectiveness of binaural beats was uncertain and contested, with studies showing conflicting results. Some studies suggest that it may help calm the mind and induce a meditative state, while others show inconclusive results.

    Full Answer >
    Filed Under:

Explore