Balloon carrying a compact package of meteorological instruments and a radio transmitter, used to sound, or measure, conditions in the atmosphere. The instruments measure temperature, pressure, and humidity, and the information gathered is transmitted back to observers on the ground. A radar target is often attached, allowing the balloon to be tracked.
Red and white are the colours of Bohemia, dating back to the 13th century. Blue represents Moravia. Unlike that of the Slovak Republic, the Czech flag is not based on the pan-Slav colours. Effective date: 1 January 1993.