![[GFH OLD wave anatomy.png]] Flow within the wave is usually smooth, with Altocumulus Standing Lenticular (ACSL) clouds marking the crest of the wave. Cirrocumulus Standing Lenticular (CCSL) clouds may also form at higher levels. These lenticular clouds (or "lennies") may exist as isolated single clouds, or relatively straight bands of clouds, downwind and parallel to the mountain range; the latter being associated with [[Trapped Lee Waves]]. Moderate to extreme turbulence typically exists below the wave flow. Under the wave crests, horizontal roll vortices, or "rotors" form the areas with the most hazardous turbulence, often marked by rotor or roll clouds. [[Conditions Associated with Wave#Moisture]] at varying levels will determine which, if any, clouds form. Wave can exist in clear air with dry conditions; locating the areas of rising, sinking, and turbulent air will be considerably more challenging. ![[wave clouds.png]] [<iframe width="560" height="315" src="https://www.youtube.com/embed/zxfDnr3FN7g?si=J7s1vd_U_NDXDP0q" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>]