For dry ascent, cpdT=Vdp and hydrostatic pressure change is dp/dz=−ρg=−g/V, so Γd=−dT/dz=g/cp. During condensation dq<0, and −Ldq>0 offsets expansion cooling, making the saturated ascent less steep.
For a saturated parcel with q=qs(T,p), use dq=qTdT+qpdp to obtain
With dilute vapor, qp≃−qs/p and qT≃Lqs/(RvT2), this becomes Γd[1+Lqs/(RaT)]/[1+L2qs/(cpRvT2)]. In terrestrial conditions the denominator's latent-heating correction dominates. Warming increases saturation humidity strongly, so latent heat increasingly compensates expansion cooling and the moist lapse rate falls. This is a statement about saturated convective adjustment, not every instantaneous environmental temperature profile.