Weather Balloon Facts

The Upper Air Observing Program of NOAA started back in the 1930s.
Balloons are either filled with helium or hydrogen, both of which are lighter than air.
The radiosonde is exposed to temperatures as low as -130˚F during its flight.
Balloon expands as it rises due to the lack of pressure. Can expand from a diameter of 5 ft. at the surface to ~30 ft. in the upper atmosphere before it pops.
In just under two hours, a weather balloon can reach altitudes higher than planes fly. Average weather balloon flights range from 60,000 ft to over 100,000 ft.
For the balloon launch to be successful, the instrument needs to reach the 400 millibar pressure level of the upper atmosphere, which is roughly about 24,000 ft.