Weather Balloons: The Lo-Fi Workhorses of Meteorology

You might have stumbled across one while hiking—a burst, synthetic rubber balloon lying on the forest floor. That strange piece of litter is almost certainly a weather balloon, and it represents one of the most effective, low-cost tools in meteorology. Despite their simplicity, these balloons have been launched twice daily for decades, transmitting data from the edge of space back to Earth.

The Surprisingly Simple Components

A weather balloon consists of just a handful of parts. The balloon itself is the "dumbest part," as Josh puts it—a neoprene synthetic rubber envelope filled with either helium or hydrogen. Hydrogen is cheaper and provides slightly better lift, but it's highly flammable (a fact the hosts note from their Hindenburg episode). Many agencies choose helium instead.

The real intelligence is in the box the balloon carries, called a radiosonde (from the French radio sonde). About the size of a shoebox, it contains three rudimentary instruments: a thermistor (a ceramic-metal rod that measures temperature), a hygristor (a humidity sensor using a lithium chloride film that reads electrical resistance), and an aneroid barometer that measures air pressure through a trigger that expands as pressure changes. A radio transmitter relays this data to the ground in near real-time.