What is the standard SI unit used to measure a hot-air balloon’s vertical climb rate?

Metres per second is the standard SI unit used to measure a hot-air balloon’s vertical climb rate.

A balloon’s vertical speed describes how quickly it is rising or descending, rather than its altitude above sea level. Pilots monitor this rate with an instrument called a variometer, which responds to changes in atmospheric pressure.

In aviation, vertical speed may also be expressed in feet per minute, especially in countries and aircraft systems using imperial aviation conventions. The unit depends on the measurement system, but metres per second is the SI form.

Vertical speed is different from altitude. An altimeter tells a pilot how high the balloon is, while a variometer indicates whether the balloon is moving upward or downward and how quickly.