What are weather balloons?

A weather balloon with radiosonde attached.
A weather balloon with radiosonde attached. Contributed

IN AUSTRALIA there are weather stations that are playing with balloons. Not your party variety balloon but huge, 1.5m monsters.

It takes more then 8.5 cubic meters of helium gas to fill these balloons. Helium is a gas that is lighter than our atmosphere and allows the balloon to rise. Technical weather instruments, stored in a lightweight, cardboard box known as a radiosonde are attached to the bottom of the balloon and the balloon is released into the atmosphere.

It speeds away from the Earth, carrying the radiosonde, which is already hard at work sending information back to the weather station.

It takes almost an hour for the balloon to reach its goal height in the stratosphere at almost 30000m. The stratosphere is the second-to-last layer before reaching outer space.

If you were in a basket at the bottom of the balloon you would be witnessing an awesome sight. You would see the blackness of outer space above you and the green/blue sphere of the earth below but you wouldn't be there for long. While the balloon ascends it also expands.

The cause of this is atmospheric pressure. The higher the balloon goes the less pressure it encounters. Now, at about 29km above the ground the balloon reaches its maximum expansion, about the size of a large truck, and it is stretched to its limit.

The rubber splits and bursts sending the radiosonde plummeting back towards the ground. Within seconds, the wind catches a small, orange parachute and slows the device's descent until it reaches the ground, sometimes 100s of km from where it was released.

This process is repeated up to four times a day, and has done for the last 70 years since scientists first discovered the balloons and the advantages of atmospheric conditions in forecasting.

Topics:  weather westys weather

Fire crews still on scene at Southern Downs blaze

Multiple fire units are at the two fires

A fire has been monitored overnight to protect structures

SCORCHER: Record-breaking temps as QLD, NSW set to sizzle

Record-breaking temperatures hit Qld and NSW with more to come

Two break-and-enters reported at Goondiwindi

Police are investigating

Police seeking information from public

Local Partners