Meteorology · MET

Orographic Mountain Waves, Rotor Turbulence & Wave Clouds

CASA Ref: CASR Part 61 MOS Schedule 3 CMET 1.3 · FAA Ref: FAA-S-ACS-6C Area I Task C (Weather Information)

Scenario & Physics Summary

Airflow over mountain ridges creating lenticular clouds, severe lee rotors, extreme downdrafts, and altimeter pressure errors.

Interactive 3D Visual Plates & Scenario Media

Orographic Mountain Waves, Rotor Turbulence & Wave Clouds Plate 1

Plate 1: Orographic Mountain Waves, Rotor Turbulence & Wave Clouds

Orographic Mountain Waves, Rotor Turbulence & Wave Clouds Plate 2

Plate 2: Orographic Mountain Waves, Rotor Turbulence & Wave Clouds

Orographic Mountain Waves, Rotor Turbulence & Wave Clouds Plate 3

Plate 3: Orographic Mountain Waves, Rotor Turbulence & Wave Clouds

Orographic Mountain Waves, Rotor Turbulence & Wave Clouds Plate 4

Plate 4: Orographic Mountain Waves, Rotor Turbulence & Wave Clouds

Aerodynamic & Operational Physics

Stable air forced upward by mountain ranges oscillates downwind forming standing mountain waves.
Lenticular clouds (ACS/CCS) mark wave crests; Rotor clouds form underneath severe turbulent eddy currents.
Downdrafts on the lee side can exceed 2,000-3,000 ft/min, exceeding small aircraft max climb capability.

CASA & FAA Exam Gotcha Alert

CASA / FAA Exam Trap: Cross mountain ridges at a 45° angle (not 90°) to allow quick turn-away if severe lee downdrafts are encountered.

Frequently Asked Questions & Exam Explanations

Why cross mountain ridges at a 45-degree angle?

It permits an immediate 135-degree turn away from the mountain if dangerous downdrafts or rotor turbulence are encountered.

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