Warm moist air arrives under an unstable thermal stratification on the windward side. Lee waves develop in the unstable stratification on the leeward side.

A strong heating of the air on the windward side, contrasting with strong cooling on the leeward side of the mountain range.

A strong large-scale wind increase up to high levels and blowing approximately perpendicular towards the mountain range under a stable thermal stratification.

Lee waves form when strong winds blow parallel to the mountain range and split up into two branches. The wind shear across the crest causes lee waves.