What instrument is used to determine the rate of climb or descent in a hot air balloon?

The instrument used to determine the rate of climb or descent in a hot air balloon is the variometer. This device provides real-time feedback on vertical speed by measuring the changes in air pressure or the rate of change of altitude. It is particularly important for balloon pilots because it helps them control their ascent or descent effectively, enabling them to navigate within different air currents and adjust their altitude as needed for safety and performance.

While altimeters measure altitude based on pressure changes, they do not provide information on how quickly the altitude is changing. Barometers measure atmospheric pressure but are not designed for measuring vertical speed specifically. Gyroscopes are used for orientation and navigation but do not relate to vertical movement in balloons. The variometer is thus the specific instrument tailored for understanding and managing climb and descent rates in hot air ballooning.