Weather Measurement Tools

1
Weather Measurement Tools
2
Thermometer

• What?
• Measures the air temperature
• How?
• Heat expands the liquid in the vacuum tube and
  causes it to rise, likewise, cold causes the
  liquid in the vacuum tube to contract.
• Measurement unit degrees Celsius (C)
• Fun Fact Thermometers were refined for studying
  weather, not for any other science.

3
Psychrometer

• What?
• Measures humidity in the air relative humidity
• How?
• By comparing the temperature of a dry bulb
  thermometer with that of a wet bulb
  thermometer.
• When water evaporates from the cloth it absorbs
  heat and produces a cooling effect on the wet
  bulb thermometer.
• If the humidity is low, more evaporation will
  occur causing more cooling and a lower
  temperature on the wet bulb thermometer. If the
  humidity is high, not much evaporation will take
  place causing less cooling and not as great of a
  difference between the wet and dry bulb readings.
  The wet bulb thermometer will most always have
  the lower temperature.
• Measurement Unit percent ()

4
Barometer .

• What?
• Measures atmospheric pressure
• How?
• The drawing shows the basic
• principles of a barometer.
• A glass tube from which the air has
• been removed is inserted into a dish of mercury.
  The air pressing down on the mercury in the
• dish forces some of the mercury up into
• the glass tube.
• Measurement unit hPa
• (hectoPascals) or mm

www.usatoday.com/weather/wbaromtr.htm
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p5_atm_pressure/barometer.gif
5
Anemometer

• What?
• Measures wind speed
• How?
• By counting the number of revolutions in a set
  amount of time. (Calibration required)
• Measurement unit usually kilometers per hour
  (km/h)

http//www.delta-education.com/productdetail.aspx?
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