Climate statistics for Australian locations

Definitions for 9am and 3pm statistics

Instruments

Relative humidity

Stevenson screen instrument shelter

Wet & Dry thermometers

Relative humidity can be calculated from the difference in temperature between two thermometers, one normally exposed and one kept moist by a wick drawing water from a small container. The moist thermometer is cooled by evaporation; the amount of cooling depending on the humidity. This photo shows both a manual and electronic thermometer arrangement.

Wind speed & direction

Terrestrial minimum temperature thermometer

Anemometer & wind vane

Wind speed and direction are normally measured at a height of 10 m above the surface. The rotating cup anemometer is commonly used to measure wind speed.

Related Links

  • This page URL: http://www.bom.gov.au/climate/cdo/about/definitions9and3.shtml
  • About climate averages: http://www.bom.gov.au/climate/cdo/about/about-stats.shtml
  • Climate averages home page URL:  http://www.bom.gov.au/climate/data/index.shtml
  • Bureau of Meteorology website:  http://www.bom.gov.au