weather

• Rain Gauge


  • Has a fixed diameter so that they collect the same amount of water
  • Comparisons can be made
• Rain Gauge


  1. Funnel (A) to collect the water

  2. Container to collect water, which may be graduated

  3. Emptied once every 24hrs
• Rain measurement


  Measured in millimetres
• Rain Gauge


  • Sunk into the ground, but not level, so splashes or surface water can't get in
• Anemometer


  • Three light rotating cups (mounted on a high pole) are blown around by the wind
  • The revolutions are counted & converted into m/s, km/h or knots
• Sunshine Recorder (Heliograph)


  • Burns a timeline
  • Trace sunshine not the hours of daylight
  • The glass ball focuses the light
  • This burns a line onto the card
• Max-min thermometer


  • Max thermometer contains mercury & min contains alcohol
  • As temp. rises, mercury expands & pushes up a metal index, and when it cools, mercury contracts, and the index is left in place at highest temp
  • As temp. falls, alcohol contracts & pulls metal index with it; but as alcohol expands, it flows past index, leaving it at its lowest temp
  • Both indexes read from the bottom once every 24hrs
• Wet & dry bulb thermometer (hygrometer)


  • A dry bulb is a normal mercury thermometer, and it measures actual air temperature
  • The wet bulb is the same but is covered with a fine cloth connected to a water reservoir
  • Water evaporates from the cloth & cools temperature so it reads a few degrees lower than air temp
  • Both wet & dry bulb temperatures read
• Barometer


  • An aneroid barometer has a vacuum chamber
  • As air pressure rises & falls, the chamber contracts & expands
  • Levers conduct this movement to a spindle, which moves the pointer on the dial, which records the air pressure in mmHg
• Wind Vane


  • The wind blows the fletching so that the arrowhead points into the wind
  • Mounted on high places (rooftops)
  • Make sure no trees are blocking