Equilibrium DALR Parcel motion Parcel motion Parcel motion Parcel motion 1 2 3 4 P a r c e l o f a i r w i t h m o v e $^{m}$e nt + + + + – – – – Temperature Temperature Temperature Temperature –T = cooler than surrounding air +T = warmer than surrounding air DALR = dry adiabatic lapse rate Figure 9-24.  Parcel displaced vertically and oscillating around its equilibrium level. Figure 9-25.  Mountain lee wave system. Cap cloud Lower turbulent zone Roll cloud ACSL CCSL Tropopause Lee wave region Height (thousands of feet) Temperature Wind Wind Stable Layer Main downdraft Main updraft 30 25 20 15 10 5 Temperature Horizontal distance Temperature Wind velocity  Standing Lenticular Cirrocumulus Clouds (CCLS) Altocumulus Standing Lenticular Clouds (ACSL) topography has many complex, three-dimensional features,  such as individual higher peak, large ridges, or spurs at right  angles to the main range. Variations can occur when a north- south range curves to become oriented northeast-southwest.  In addition, numerous variations of the wind and stability  profiles are possible. 9-17