When I was a kid, I would get the Edmund Scientific catalog in the mail, and see weather balloons for sale. For some reason, these fascinated me, figuring they were relics from the 1940's.
I assumed these days the only kind of balloons in common use were those at the Thanksgiving Day Parade here in NYC:
But I just started taking an online meteorology class, and in one of the introductory lessons, I was shocked to discover that weather balloons actually still, to this day, play a critical part in gathering data on the atmosphere. According to NOAA, "At the present time, there is no single observing system (e.g., satellites and ground-based remote sensors) that can match the vertical data resolution (about 30 meters or less) and height coverage (more than 30 km) obtained with" weather balloon-launched instrumentation. And so, twice a day at noon and midnight GMT, at nearly 900 locations worldwide (92 locations in the US and its territories alone), balloons are simultaneously launched to give us a global snapshot of the condition of the atmosphere.
As each balloon floats skyward towards its ultimate doom, it carries an inexpensive radiosonde which measures atmospheric pressure, relative humidity and temperature, all of which is transmitted to and recorded from the ground. Here's two great photos from the National Weather Service in El Paso, Texas showing the setup and the radiosonde:
According to NOAA, the "... flight can last in excess of two hours, and during this time the radiosonde can ascend to over 35 km (about 115,000 feet) and drift more than 200 km (about 125 miles) from the release point." The balloon eventually bursts, and the radiosonde parachutes back to earth. Return instructions are included on each radiosonde, but less than 20% are sent back for reconditioning.
The data recorded during the flight is plotted out as a "sounding" (below is the most recent sounding covering here in NYC):
(Details on how to read this chart here.)
Here's a guy "Learjet66" in Australia who caught one popping with his telescope:
The ancient "MICROART" ground tracking system is currently being upgraded to utilize modern technology for more accurate readings. They launch balloons out on Upton, Long Island, (and their tracking system is being upgraded in June), they are open to the public on summer Sundays and so that's going on my list of things to check out.
I'm writing this just after 8pm local time, and it's kind of amazing and eerie to think that one of these balloons is up above me somewhere, drifting along, following, "the prevailing wind and ... dropping into the North Atlantic Ocean, never to be recovered".