Abstract: An atmospheric sounding unit is provided which is capable of being launched from an aircraft. The unit includes atmospheric sounding instrument such as a rawinsonde for, in operation, providing desired atmospheric soundings; a balloon connected to the sounding instrument; a gas source, e.g., a gas tank, for a lighter-than-air gas; an arrangement for filling the balloon with the gas; and a sensor for sensing the approach of the unit to the Earth and for providing release of the balloon with the sounding instrument connected thereto from the remaining components of the unit when a predetermined approach condition, e.g., contact with water, is sensed. Upon release, the balloon is permitted to ascend and the sounding instrument produces soundings during the ascent of the balloon into the atmosphere. A system of parachutes controls the descent of the unit after the launching thereof from the aircraft.