Vaisala radiosondes were extensively tested in various climates and environments. Pictured a radiosonde launch in the sierras of Argentina in the '50s.

A Vaisala radiosonde manufactured in 1955.

Performing upper air observations in the late 1950's.

Vaisala participated in the first international radiosonde comparison which was organized in Payerne, Switzerland, in 1950.

The Vaisala aerological station at Vaisala in the 1950's, where regular soundings have been performed since 1958.