Watching Weather Balloons on Ham Radio

UC Berkeley’s Amateur Radio Club (archive) and the East Bay Amateur Radio Club (archive) in California launched a balloon with a tracking device Saturday, which allowed radio amateurs to see how far the balloon went, how high it went and how fast it was going. After launching the balloon on the UC Berkeley campus, the hobbyists followed it in their cars to where it landed near Sacramento.

Balloons like this can be fun to track for amateur radio operators like myself, but they can also help us watch the weather. The National Weather Service launches weather balloons from points all around the country every day. This allows them to see actual conditions, such as temperature and wind speed, from several thousand feet in the air.

The balloon UC Berkeley launched today wasn’t fitted with a bunch of instruments, but it did show us the upper-level winds as it went up. Here’s a map of its trip:

Cool, so it went from Berkeley to the other side of Sacramento. But what we can also look at is how high up it went and how fast it went:

The altitude is pretty straightforward. It reached 107,553 feet (20.37 miles) high before the balloon eventually popped and the device came back to earth by a parachute. That altitude is considered to be the edge of space. The atmosphere that high is around 1/100th the thickness it is at sea level. The speed the device went is a different story. The device reached 103.8 mph, but why did it slow in the middle?

The reason behind the two peaks in speed is because around 30,000 feet, the device went through the jet stream. You may be familiar with the jet stream – strong winds at the elevation airplanes fly that guide weather systems. Today the jet stream was situated right over Northern California, as seen on the map on the right. Winds in the jet stream over Northern California

Winds in the jet stream over Northern California exceeded 120 mph when the balloon was in flight, which propelled the balloon to

speeds in excess of 100 mph during its first pass through the jet stream. Its second pass through didn’t last as long since it was falling back to earth, so it “only” got above 90 mph during that period of time.

Above the jet stream, winds are significantly weaker. At 60,000 feet above the Bay Area, they were barely reaching 20 mph. Going even higher up to near 100,000 feet gets you even slower winds.

You may also notice that the wind direction is a little different at different elevations. The part of the device’s journey in the jet stream took it in a northeasterly direction. When it was above the jet stream, it went more toward the east.

For someone like me who is both an amateur radio operator and a wannabe weatherman, this is about as fascinating as it gets. Not only was I able to watch as they played with cool equipment that I wish I could afford, but I got to see in real time what the winds in the upper atmosphere are like.

The balloon was tracked using a system called APRS (Automated Packet Reporting System). The general idea is that a radio beacon sends location and speed data on a certain frequency, which is heard by a nearby station that is connected to the internet. APRS beacons can be attached to and track just about anything if you have a ham radio license and some creativity.

You don’t need a ham radio license to watch things on APRS by going to http://aprs.fi. On there you can search things globally by callsign (the balloon was W6BB-11, for example). You can also just zoom into your city and see what is going on. This particular website also integrates AIS information in may areas. AIS is a system similar to APRS that is used in many ocean-going vessels. 

If you read clear down to this point, you might be interested in learning more about becoming a ham radio operator. If so, just comment on this post and I’ll point you in the right direction. Amateur radio can be used for experiments, emergency communications or to make contacts around the globe – I even talked to Ireland just today.

Note: This post was edited to correct an error reporting that Washington State Ferries were connected to APRS. They instead send data through AIS, which can be seen online alongside APRS data through some sources.