Mountain Weather
Mountain Weather is a core knowledge area on the Aviation Weather FAA written exam. This hub collects our 5 in-depth, ACS-aligned mountain weather articles — each written in plain English and grounded in the official FAA handbooks. Work through them below, then drill the topic with practice questions.
Mountain Waves and Gravity Waves: How Terrain Bends the Wind
Mountain waves and gravity waves form when stable air crosses a mountain ridge, creating oscillating disturbances that can reach above 60,000 ft and produce turbulence severe enough to structurally damage an aircraft.
Mountain-Wave Turbulence and Horizontal Roll Vortices Aloft
Mountain-wave turbulence forms when stable air crosses a ridge, generating gravity waves, Kelvin-Helmholtz shear waves, and rotor zones that can extend above 60,000 ft and cause structural damage with little visual warning.
Mountain Obscuration and Density Altitude Hazards
Mountain obscuration and density altitude hazards combine reduced visibility, terrain-induced turbulence, and degraded aircraft performance into some of the most dangerous flying conditions a pilot can encounter.
Upslope, Valley, and Mountain Fog in High Terrain
Upslope, valley, and mountain fog form through distinct mechanisms in high terrain and can rapidly reduce visibility to zero, making them critical hazards for mountain flying operations.
Mountain Icing and Orographic Cloud Hazards
Mountain icing and orographic clouds—formed when stable, moist air is lifted over terrain—create serious structural icing, turbulence, and wave hazards that pilots must recognize and avoid well before entering mountainous areas.
More Aviation Weather subjects
Articles are original summaries grounded in the public-domain FAA handbooks and cite their source. ACS-aligned study aids — not a substitute for the official handbooks or regulations.