Weather Instuments

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Weather Instuments
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Thermometer
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• Thermometers measure air temperatures.
  Thermometers work because matter expands when
  heated. Most thermometers are closed glass tubes
  containing liquids such as alcohol.

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Barometer
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• A barometer measures air pressure.
• There are two types of Barometers Mercury
  Barometer and Aneroid Barometer.

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Aneroid Barometer
Mercury Barometer
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• A Mercury Barometer consists of a glass tube
  inserted into a dish of mercury or colored
  denatured alcohol.

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• The surrounding air presses down on the mercury
  in the dish and forces some of the mercury up
  into the tube. The height to which the mercury
  rises in the tube is directly proportional to the
  atmospheric pressure.

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Hygrometer
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• A hygrometer
• measures the humidity of the air. One of the two
  thermometers has a wick (cloth cover) which is
  dipped in distilled water.

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• Evaporation of water from the wick on the wet
  bulb thermometer leads to cooling.
• Using a Relative Humidity Table, the temperature
  difference between the two thermometers gives the
  relative humidity of the air (in percent).

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• This is an example of the type of table you would
  use. Your book might also have an example.

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Anemometer
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• An Anemometer measures the wind speed. The cups
  catch the winds, turning a dial attached to the
  instrument.
• Think you could build one of these?

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WIND VANE
Shows the wind direction
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Rain Gauge
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Time for a little review!
Ready?
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• Thermometer
• Barometer
• Psychrometer
• Wind Vane
• Rain Gauge
• Anemometer

1. If I wanted to find out if the pressure was
   rising, Id use which of the following?
2. Used to determine the relative humidity.

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• Thermometer
• Barometer
• Psychrometer
• Wind Vane
• Rain Gauge
• Anemometer

• 3. Can help you find out the wind speed.
• 4. If I wanted to know the difference between the
  temperature inside and outside of the classroom.

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How did you do? Here are the correct answers

• 1.Barometer
• 2. Psychrometer
• 3. Anemometer
• 4. Thermometer