Estimates of the importance of the compressional β effect under uniform rotation using ℜ[𝒲_comp], as defined in Eq. (19), for the compressible setup. A negative value of ℜ[𝒲_comp] implies that the compressional β effect promotes retrograde propagation, while a positive value implies that it promotes prograde propagation. Column (a) denotes the HFR mode with m = 10, column (b) denotes the n = 1 equatorial Rossby mode with m = 3, and column (c) denotes the prograde columnar mode with m = 3. For all modes, we normalize ℜ[𝒲_comp] such that its maximum absolute value is 1.