Why we use weather balloons
Balloon-based weather observations provide precise measurements of:
- temperature
- pressure
- humidity
- wind speed and direction.
These observations help us understand Earth's climate.
We also use this data in forecasts and warnings, to protect life and property in Australia.
Data from weather balloons also helps Australia meet its international obligations. We are required to provide weather and climate-related measurements of the upper atmosphere, under the Convention of the World Meteorological Organization.
Filling a Bureau weather balloon with hydrogen gas at Broadmeadows in Victoria
How a weather balloon works
A weather balloon is filled with hydrogen gas so that it can rise into the atmosphere. It carries a:
- radiosonde – a device that takes measurements
- parachute or foil-coated cardboard target to slow its descent. The target is shaped like a 4-sided pyramid.
During the radiosonde’s flight, it constantly sends temperature, humidity and pressure data to receiving equipment on the ground.
This equipment processes and converts the data into weather messages. The information is also displayed as an aerological diagram, used by forecasters to assist in forecast and warning services.
How high weather balloons go
A weather balloon can reach an altitude of 16–35 km in the upper atmosphere.
When a weather balloon bursts
As a weather balloon rises, the pressure outside it decreases. The pressure of the hydrogen gas inside the balloon causes it to expand and it will eventually burst. When this happens partly depends on the size of the balloon and the initial pressure in the balloon.
After the balloon pops, it descends to Earth and carries the radiosonde and other equipment with it.
The balloon may contain no gas or be partly inflated when it lands.
Weather balloon in flight, with a cardboard target attached
If you find a weather balloon
Inflated or partially inflated weather balloon
Keep at least 10 m away from the balloon. It may contain highly flammable hydrogen gas.
Call 000 immediately and ask for Fire Brigade assistance.
Hydrogen gas can explode when exposed to an ignition source such as:
- a flame
- electromagnetic signal
- low level static electricity.
Empty weather balloon
Balloons that have burst do not pose an immediate risk and can be handled. Wash your hands afterwards, as they are lined with talcum powder that may irritate your skin.
Empty balloons may appear very torn and shredded.
Disposing of the weather balloon and other items
The radiosonde, cardboard target or parachute that may be attached to the balloon do not pose a risk.
You can dispose of the balloon and the attached items in your household garbage and recycling. Do not burn or incinerate the radiosonde.
When to inform us
If you've found one of our weather balloons, we'd like to know. Other organisations in Australia also release weather balloons, such as research institutes and emergency services.
Identify the owner
Our radiosondes have a sticker that says 'Australian Bureau of Meteorology Radiosonde'.
If there is a different sticker or none at all, the balloon is not ours. Look for information to identify the owner, and contact them.
If you can't identify the owner, dispose of the items.
If the weather balloon is ours
Report your find to us using the feedback form on our Contact page. Tell us:
- the 8-digit code on the lower right hand corner of the radiosonde – this gives us details about where and when the balloon was released
- where you found the balloon
- when you found it.
If you find one of our weather balloons, send us the 8-digit code at the bottom right of the radiosonde. We use this to get details of the balloon launch.
How many weather balloons are released?
Worldwide, weather balloons are released from about 1,300 locations each day.
We release about 42 weather balloons a day, or about 15,000 a year. They are launched from 38 locations across Australia and its offshore territories, including Antarctica.
Environmental impact of weather balloons
We try to reduce our impact on the environment wherever possible. To limit the environmental impact of weather balloon flights, we:
- pursue alternate upper atmosphere technologies
- use more environmentally-friendly materials
- work with suppliers to make continual improvements.
Weather balloons are a critical part of our observation network. They will continue to deliver vital weather data into the future.