An idealized reversible work cycle defined for any system, but usually limited, in meteorology, to a so-called perfect gas. The Carnot cycle consists of four states: 1) an isothermal expansion of the gas at a temperature T1; 2) an adiabatic expansion to temperature T2; 3) an isothermal compression at temperature T2; and 4) an adiabatic compression to the original state of the gas to complete the cycle. In a Carnot cycle, the net work done is the difference between the heat input Q1 at higher temperature T1 and the heat extracted Q2 at the lower temperature T2. The atmospheric general circulation and some storms, notably hurricanes, incorporate a process similar to a Carnot cycle. See Carnot engine, thermodynamic efficiency.