Weather Education

Weather Balloon Launch to Capture Data

This is the story of a man and a balloon.

My name is Jim Salzwedel and I'm a Hydrometeorological Technician

Jim is preparing to launch a weather balloon with radiosonde in Slidell, Louisiana.

We're an official upper air site for the National Weather Service.

The weather balloon carries instruments to measure weather in the upper air as it rises.

The data is highly critical for the weather modeling process... to get the best available forecast.

This launch is choreographed twice daily with launches at over 90 locations in the US and another 700 worldwide at...

23z and 11z, locally during daylight time it's 6 in the morning and 6 at night.

This step is pretty obvious.

Filling up the weather balloon...

...and then tying it closed. There's nothing worse than letting a balloon get out of your hands! Before the launch Jim is on a computer...

Looking at the upper wind flow so we have a good idea of where the radiosonde is going to travel after we release.

The radiosonde is then checked for accuracy.

We compare that with weather instruments we have here at the office, to make sure the data is correct before we actually release it.

Radiosonde Radiosonde held in hand

A battery powers the sensors for temperature, humidity and pressure, as well as a GPS unit used to help determine wind. The radiosonde...

... transmits the data back to the telemetry receiving system, that way we can get the data real-time.

Because the instrument may end landing in your back yard...

We put this sticker on here to let folks know it's a harmless weather instrument.

...harmless but the balloon may contain hydrogen.

You want to take great care and caution in handling that because it is a flammable gas

...also, if you find a recently used radiosonde, the batteries might be hot or hissing. Just let them cool and quiet down before handling.

But it's not a hazard.

And now, it's launch time. On a sunny day...

We watch out for aircraft. We have to be careful with different obstacles, trees, power lines.

But on a stormy day...

You might only have a 5 or 10 minute window before the next line of storms.

Either way the data is valuable.

Typically, when we release the balloon it's right around 5 to 6 feet in diameter. But as it goes through the atmosphere and expands through the higher altitudes, this actually expands to almost 20 feet or greater before it actually bursts. Usually, at our office our weather burst at over 105,000 feet.

...that's 20 miles up. Now how far it travels...

really depends on how strong the upper level winds are.

Radiosonde Radiosonde return envelope

The balloon may travel a dozen miles away or a couple hundred miles away. No matter how far it travels, it's all for the data.

We find burst weather balloons in the News 5 area regularly but most fall in the woods so they are never found. About 20% are found nationally and returned to the National Weather Service for refurbishing. It's pretty amazing to think these are launched twice a day, all over the Earth, day or night, in all type of weather. Alan Sealls, News 5.

Mobile County

Baldwin County

Northwest Florida