Instruments used for observations

How do you record temperature?

The most commonly used thermometer in the Bureau has been the liquid-in-glass thermometer, consisting of a reservoir of liquid (the bulb) and a slim capillary tube through which the liquid rises when warming and descends when cooling. More recently an electronic sensor connected to an automatic weather station is used instead of the liquid-in-glass thermometer. Information on thermometers used by the Bureau is available on the 'Observation of air temperature' page.

Definitions of various temperature statistics are available on the 'Climate statistics for Australian locations' page.

How do you record rainfall?
The standard instrument for the measurement of rainfall is the 203mm (8 inch) rain gauge. At automatic weather stations 'tipping bucket' rain gauges are used. More information about rain gauges is available on the Bureau's 'Observation of rainfall' page.
What are ceilometers and visibility meters?
Ceiliometers provide an estimation of cloud height, while visibility meters help estimate the maximum distance a 'reference' object is visible under the atmospheric conditions prevailing at the time of observation. Information about ceilometers and visibility meters is available as part of the Bureau's Aviation Reference Material http://www.bom.gov.au/aviation/data/education/ceilometer-visibility.pdf.
How do I know what equipment has been used to make observations?
The Bureau's Climate Data Online product provides access to station metadata, which include a summary of the equipment installed at a site. You can also download station metadata files via our tool in the section About data and observations. The station metadata file for Alice Springs provides an example of the types of information available.