Mountain Flying

Mountain Wave & Rotors

Above about 25 knots blowing across a ridge, the air stops flowing smoothly and starts to wave — like water over rocks in a streambed — with strong up- and downdrafts downwind and violent rotors beneath the crests. Add moisture and the sky draws you a picture. Change the conditions and see what forms.

Air flowing across the ridge →

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Wind across the ridge15 ktAbove ~25 kt the flow breaks into a standing waveAir stabilityNeutralStable air holds cap clouds; unstable air builds convectionMoistureDryMoisture makes the flow visible as cloud

Mountain Wave & Rotors

What's forming