Instruments used to measure weather( junior cert geography)

thermometer

used to measure temperature - when temperature rises alcohol in one tube expands and pushes mercury up in the the other tube. works in the opposite way when temperature falls

barometer

measures air pressure in millibars or hectopascals

hygrometer

measures humidity - measured in %RH

Stevenson screen

A box that contains weather instruments and shields them from direct sunlight

wind vane

measures wind direction - the sail is blown forward by the wind, the head of the arrow points in the direction the wind blows

anemometer

used to measure wind speed - it has 3 cups which rotate when the wind blows, the faster the wind the faster the cups blow

Campbell Stokes Recorder

Measures sunshine - a glass ball focuses sun rays onto a heat sensitive paper

Rain guage

measures the amount of precipitation/rainfall