Home Made Barometer

Discussion in 'Back to Basics' started by RightHand, Oct 30, 2005.

  1. RightHand

    RightHand Been There, Done That RIP 4/15/21 Moderator Moderator Emeritus Founding Member

  2. Quigley_Sharps

    Quigley_Sharps The Badministrator Administrator Founding Member

    Good info RH thanks for the links
  3. melbo

    melbo Hunter Gatherer Administrator Founding Member

  4. RightHand

    RightHand Been There, Done That RIP 4/15/21 Moderator Moderator Emeritus Founding Member

    A barometer is a relatively simple instrument that measures the pressure of surrounding air (atmospheric pressure).
    "Atmospheric pressure" is measured in terms of large--as large as 2.5 million square kilometres high pressure or low pressure areas. In a high pressure area (air molecules are closer together), the air in the atmosphere is heavy and therefore falling gently. This produces clear skies and fair weather. By contrast, the air in a low pressure area (air molecules are further apart) is gently rising. As it rises, the air cools. Water vapour condenses into tiny water droplets around microscopic particles floating in the air, and clouds result. If more and more water vapour continues to condense, it will eventually rain or snow.
    In the homemade barometer, air pressure forces water up the neck of the bottle. The further up into the bottle that the water moves, the higher the air pressure and the drier the weather. The homemade barometer can be sensitive to the immediate air temperature and other conditions and, therefore, may not always correspond to official atmospheric pressure readings.
    Topics: Weather Conditions; Air; Atmosphere; Measure
    Clear bottle (e.g. pop bottle); clear, wide-mouthed jar (bottle should fit snugly but not air-tight into the mouth of this Jar); water; food colouring; permanent marker.
    1. You must make this barometer when it is raining or snowing! The barometer will not work unless It's made when there Is low pressure.
    2, Add a bit of food colouring (red looks rather nicer) to some water.
    3. Pour enough coloured water into the jar so that when the bottle is inverted into the jar a little of the water rises up into the neck of the bottle.
    4. Once you have the right level of water in the jar, let the barometer (bottle inverted into jar) sit for about 15 minutes.
    5. Take a look at the water level in the bottle's neck. Mark the level with a marker. This is the low pressure mark. Add three more marks, 1 cm apart, above the lowest mark. The top mark indicates high pressure.
    6. Take a barometer reading at least a couple of times a day (i.e. once in the morning, once in the evening). Water at the lowest mark indicates wet, stormy weather; on the second or third mark it indicates a change in weather; and at the fourth mark it indicates settled, dry weather.
    7. When the water in your barometer begins to evaporate away, you will need to make the barometer again.
    Because air at higher altitudes compresses air below It, about half the total weight of the atmosphere is concentrated In the 5 km layer closest to Earth. As you climb a mountain, there is less and less air above you. For example, at the top of Mount Everest (8,848 m) the weight of the air is only one third that at sea level. "Thinner" air at high altitudes makes it difficult for humans to breathe, and also affects the temperature at which water boils (which mean6 It takes longer to cook food).
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