The radiosonde is a meteorological instrument which is hung from a balloon released into the atmosphere. As the balloon goes up the radiosonde records air pressure, temperature and relative humidity and sends this information back to earth via radio waves. It allows metrologists to measure changes in atmospheric conditions and, hence, make weather predictions.

This radiosonde is one of the earliest used in Australia. Amalgamated Wireless (Australasia) Ltd started producing these instruments in Australia in 1947. It has had sections cut away from it and was probably used as an educational model to illustrate its workings. It also has a detailed description of how it works in text on its side.

This instrument remains significant due to its pioneering role in Australian science and its association with Australia's astronomers and meteorologists.

Since the 1980s radiosondes have not been made in Australia. Only imported ones are used. The museum also holds a copy of a related manual on radiosondes published by the Commonwealth of Australia Department of Interior Meteorological Branch in 1949.

Geoff Barker, Assistant Curator, March 2007

References
Tideman, B., The Radiosonde in Australia, attached letter to Powerhouse Museum Blue File, 1992
Vaisala News, number 92, Vaisala Finland, 1981
Hopkins, E. J., 'Radiosonde's; an Upper Air Probe', 1996, cited in http://www.aos.wisc.edu/~hopkins/wx-inst/wxi-raob.htm, October, 2007

In 1943 Radiosondes based on a design by Diamond-Hinman were first introduced to Australia. These were a part of wartime attempts to predict and measure weather systems. This design remained relatively unchanged for the next forty years. In 1945 the first Australian-made instruments were introduced by Radio Corporation Ltd under the ASTOR label.

In 1947 Amalgamated Wireless Australasia Ltd, (AWA), began to make small numbers and in 1959 were able to expand production after the introduction of six new stations.

A major shift in the design of the Radiosonde came about in 1981 with the introduction of the Vaisala RS80. Made in Finland, they were much smaller than previous versions and required no assembly or calibration before launch. Small balloons made them more economical and also less of an air safety risk.

In 1990 a personal computer-based radiosonde computation system was introduced, enabling the meteorological data to be updated automatically rather than manually.

Nowadays balloons are sent up twice a day, at midnight and midday, from stations around the world. They record information until they are 30 kilometres above sea level, when air pressure causes the balloon to burst. The information they collect (ROAB) is collated and transmitted to National Meteorological Centres, often within a matter of hours to aid in weather predictions.

References
Tideman, B., The Radiosonde in Australia, attached letter to Powerhouse Museum Blue File, 1992
Vaisala News, number 92, Vaisala Finland, 1981
Hopkins, E. J., 'Radiosonde; an Upper Air Probe', 1996, cited in http://www.aos.wisc.edu/~hopkins/wx-inst/wxi-raob.htm, October, 2007

Radiosonde, metal / cardboard / fabric / plastic, made by Amalgamated Wireless (Australasia) Ltd, Sydney, New South Wales, Australia, 1947-1948

The Radiosonde consists of electronic components held within a waterproofed cardboard box that has been insulated on the inside. Printed on one side of the box is text explaining the function of the Radiosonde. Sections of the cardboard box have been cut away to reveal some of the electronic components that make up the instrument. A wire with the lead weight constitutes the lower half of the dipole transmission antenna. It has an "S" shaped ventilation duct and a single aneroid pressure cell. At the top of the Radiosonde is a white fabric strap with a metal o-ring attached.

Made: Amalgamated Wireless Australasia Pty Ltd; Sydney, New South Wales; 1947 - 1948

Text on one side of the Radiosonde reads 'RADIOSONDE / PROPERTY OF THE COMMONWEALTH OF AUSTRALIA / THIS INSTRUMENT WAS RELEASED FROM A WEATHER / STATION AND CARRIED ALOFT BY MEANS OF A / SOUNDING BALLOON WHILE ALOFT THE INSTRUMENT / TRANSMITTED RADIO SIGNALS WHICH INDICATED TEMP- / ERATURE, HUMIDITY AND PRESSURE OF THE ATMOSPHERE / THROUGH WHICH IT PASSED. WHEN THE BALLOON BURST / THE INSTRUMENT DESCENDED SLOWLY BY PARACHUTE'.

92/414

1947 - 1948

210 mm

120 mm

260 mm