Final answer:
Instruments in an aircraft measure changes in atmospheric pressure, which is then converted into readable gauges that inform the pilot about altitude and rate of climb or descent.
Step-by-step explanation:
An instrument that reacts to changes in pressure conveys important information to a pilot regarding altitude and rate of climb/descent indication. These instruments include various gauges that measure atmospheric pressure. As an aircraft changes altitude, the pressure changes. The pressure results in a force that is converted into a mechanical movement in an aneroid gauge or into electrical signals in other types of sensors. This force is then transduced into a readout that the pilot can understand, typically as numbers or needle positions on a dial, indicating the altitude and rate of climb or descent.