Bernoulli's equation as I understand it is an expression (or possibly a consequence) of conservation of energy in an incompressible fluid flow. My question is: how can the "standard" Bernoulli's equation ever apply to an ideal gas? Wikipedia gives a different version of Bernoulli's equation for a compressible fluid, which assumes adiabatic compression and has a coefficient with some gammas in front of the pressure term. Shouldn't this version always apply to an ideal gas fluid, and not the standard equation? I understand that there are arguments that an ideal fluid basically doesn't significantly compress if it's significantly subsonic, but I don't see how these arguments affect the equation of state of the fluid, which is what tells us how the internal energy of the gas behaves.