Moist stratified turbulence is studied in a two-dimensional Boussinesq system
influenced by condensation and evaporation. The problem is set in a periodic
domain and employs simple evaporation and condensation schemes, wherein both
the processes push parcels towards saturation. Numerical simulations
demonstrate the emergence of a moist turbulent state consisting of ordered
structures with a clear power-law type spectral scaling from initially
spatially uncorrelated conditions. An asymptotic analysis in the limit of rapid
condensation and strong stratification shows that, for initial conditions with
enough water substance to saturate the domain, the equations support a
straightforward state of moist balance characterized by a hydrostatic,
saturated, vertically sheared horizontal flow (VSHF). For such initial
conditions, by means of long time numerical simulations, the emergence of moist
balance is verified. Specifically, starting from uncorrelated data, subsequent
to the development of a moist turbulent state, the system experiences a rather
abrupt transition to a regime which is close to saturation and dominated by a
strong VSHF. On the other hand, initial conditions which do not have enough
water substance to saturate the domain, do not attain moist balance. Rather,
the system remains in a turbulent state and oscillates about moist balance.
Even though balance is not achieved with these general initial conditions, the
time scale of oscillation about moist balance is much larger than the imposed
time scale of condensation and evaporation, thus indicating a distinct dominant
slow component in the moist stratified two-dimensional turbulent system.Comment: 23 pages. 9 figure
