Unit 8: Weather Instruments

Posted by KCRG-TV9 First Alert Weather on Wednesday, May 13, 2020

How do we measure the weather?

  • Personal weather stations
  • Aircraft data
  • Airport weather stations


  • Tells us the temperatures
  • Filled with a liquid
  • When it gets warmer, the liquid expands and goes up in the tube


  • Tells us the wind speed
  • The faster the wind, the faster the cups spin around

Wind/weather vane

  • Tells us the wind direction
  • The back has a fin that spins around with the wind to determine the direction
  • North. South, East, West
  • Winds from the southwest, we start to warm up,
  • North of northeast winds will bring cooler air

Rain Gauge

  • Tells us how much rain has fallen
  • Collect rain as it falls, measure water
  • Wind can cause some issues with measuring rain. Some rain may miss the gauge
  • Heavy rain can also cause some errors with automated equipment

Measuring Snow

  • Can use a ruler or a snow core samplers
  • Snow core campers get a core of snow (like an apple core) and can measure the depth or melt it down in a warm pan or room. Can give us a ratio
  • Snow ratios can differ
  • Make sure you are away from drifts when measuring or an area where the wind won’t impact the measurement


  • Tells us the air pressure - the weight of the air above us
  • Liquid or needle moves up and down, like a thermometer

Doppler Radar

  • Tells us where precipitation is like rain or snow
  • Sends energy out
  • If there’s anything there it’ll come back
  • If there’s nothing, it’ll show up blank
  • Pretty much, how much is being reflected back to the radar
  • Radar can pick up on rain in the upper levels that may not be reaching the ground

Weather Balloons

  • Tells us the weather up through the atmosphere
  • Send the information back until the balloon pops
  • Can tell us what the winds are doing aloft, find out what the temperature is doing in the upper levels or dew point, etc.
  • NWS launches balloons twice a day
  • If you ever see one, send it back to NOAA through the mail


  • Usually used by the National Hurricane Center to drop down into the center of a hurricane
  • Flown into a hurricane by Hurricane Hunters


  • Take pictures of the clouds
  • Sit 23,000 miles above the earth
  • Visible, infrared, and water vapor

Lesser-Known Instruments


  • Measure humidity using two thermometers

Chilled Mirror Hygrometer

  • Measure dew point using chilled mirrors


  • Measure cloud coverage and height using vertical beam
  • Most sense to 12,000 feet
  • Cloud height can help determine cloud type


  • Measures visibility
  • Every airport has one & is important for pilots

Hail Pad

  • Measures hail size
  • Imprinted even after the hail has melted to get a good measurement

Wind Profiler

  • Acts like a Doppler Radar to measure wind speed and direction directly above the profiler
  • Still used today, mainly in Tornado Alley

Campbell-Stokes Recorder

  • This device measure sunshine