The cups catch the wind, turning a dial attached to the instrument. The dial shows the wind speed. Barometer Measures air pressure in millibars. An Italian scientist named Torricelli built the first barometer in 1643. Thermometer Measures air temperature .
Thermometers work because matter expands when heated.
When air around the thermometer heats the liquid, the liquid expands and moves up the tube. Rain Gauge Measures the amount of rainfall in mm. Not only does a rain gauge measure rainfall, but also all other forms of precipitation.