Before he lets it go, the weatherman walks about 20 metres from the shed where he filled the balloon and into an open space.

''The wind has a wave effect as it rolls over the building,'' Mr Black said after the orb had sped into the sky.

''If I had let go too early, the balloon would have crashed into the ground or back into the building.''

It is dangerous work, and the chance of being knocked off his feet by the wind is just one of the risks.

The balloon is full of highly flammable hydrogen gas that could ignite from just a little static electricity - Mr Black wears a flame-retardant, static-proof suit as a safety measure.

What looks like a giant version of child's play is in fact a key part of global weather prediction.

Co-ordinated by the World Meteorological Organisation, thousands of weather balloons are launched at the same time every day, all around the world. More than 100 are released in Australia alone.

Each carries a radiosonde, which measures atmospheric data such as air pressure, temperature, humidity, wind speed and direction.

Australia's Bureau of Meteorology has been introducing fully automated launching sites or remote launching devices across the nation.

But Australia's four Antarctic stations still do manual releases because the automated processes are limited by strong winds.

Inside Casey station's meteorological office, staff monitor the balloon's progress on a computer.

''It's going up very fast,'' a forecaster said.

At 1200 metres in altitude, the balloon is recording wind speeds of 150km/h - strong enough to blow an average-sized man off his feet.

Colin Cosier is travelling in Antarctica with Nicky Phillips as part of the Australian Antarctic Division's media program.