Editing Lee wave (section)

==Clouds==
[[File:Wave win.jpg|thumb|A wave window over the [[Bald Eagle Valley]] of central [[Pennsylvania]] as seen from a [[Glider (sailplane)|glider]] looking north. The wind flow is from upper left to lower right. The [[Allegheny Front]] is under the left edge of the window, the rising air is at the right edge, and the distance between them is 3–4 km.]]

Both lee waves and the rotor may be indicated by specific [[wave cloud]] formations if there is sufficient moisture in the atmosphere, and sufficient vertical displacement to cool the air to the [[dew point]]. Waves may also form in dry air without cloud markers.<ref name=Pagen/> Wave clouds do not move downwind as clouds usually do, but remain fixed in position relative to the obstruction that forms them.

* Around the [[Crest (physics)|crest]] of the wave, [[Adiabatic process#Adiabatic heating and cooling|adiabatic expansion cooling]] can form a cloud in [[shape]] of a [[Lens (geometry)|lens]] ([[lenticular cloud|lenticularis]]). Multiple lenticular clouds can be stacked on top of each other if there are alternating layers of relatively dry and moist air aloft.
* The rotor may generate  [[cumulus cloud|cumulus]] or [[cumulus fractus]] in its upwelling portion, also known as a "roll cloud". The rotor cloud looks like a line of cumulus. It forms on the lee side and parallel to the ridge line.  Its base is near the height of the mountain peak, though the top can extend well above the peak and can merge with the lenticular clouds above. Rotor clouds have ragged leeward edges and are dangerously turbulent.<ref name=Pagen/>
* A [[foehn]] wall cloud may exist at the lee side of the mountains, however this is not a reliable indication of the presence of lee waves.
* A [[pileus (meteorology)|pileus]] or cap cloud, similar to a lenticular cloud, may form above the mountain or cumulus cloud generating the wave.
* [[Adiabatic process#Adiabatic heating and cooling|Adiabatic compression heating]] in the trough of each wave oscillation may also [[evaporate]] [[cumulus cloud|cumulus]] or [[stratus cloud]]s in the [[airmass]], creating a "wave window" or "Foehn gap".