Weather instruments and their use

For FOUR of the following weather elements, name a suitable instrument for measuring it and describe how the instrument works: temperature, rainfall, wind speed, wind direction, air pressure, humidity.

[8 marks — 2 per element]

Mark scheme (B1 instrument + B1 how it works per element):

• Temperature: thermometer (B1); liquid expands when heated; max/min thermometer records the highest and lowest temperatures reached (B1).
• Rainfall: rain gauge (B1); funnel collects rain into a measuring cylinder; depth of water is read in mm (B1).
• Wind speed: anemometer (B1); spinning cups rotate faster as wind speed increases; speed calculated from rotation count (B1).
• Wind direction: wind vane (B1); arrow rotates and points into the wind (i.e. shows direction wind is coming FROM) (B1).
• Air pressure: barometer (B1); aneroid barometer has a flexible metal drum that expands/contracts with pressure changes; mercury barometer measures height of mercury column (B1).
• Humidity: hygrometer/wet-and-dry bulb thermometer (B1); the difference in reading between a dry bulb and a wet bulb (cooled by evaporation) indicates relative humidity (B1). Award any four.

Total: 8 marks.