Unit 9 review: Weather Theory
A mixed check of all 4 lessons in this unit. Mixing topics is harder than one lesson at a time, and that's the point: it's how the written test and the oral exam ask.
The unit in one minute
- The atmosphere, pressure and windStandard atmosphere: 15°C and 29.92 inHg at sea level; about 2°C and 1 inHg per 1,000 ft.
- Moisture, stability and cloudsSmall temperature-dewpoint spread = clouds, fog, low visibility.
- Air masses and frontsCold fronts: fast, steep, cumuliform, thunderstorms, squall lines.
- Weather hazards: thunderstorms, icing, fog and wind shearThunderstorm ingredients: moisture, instability, lift. Mature stage is the worst. Avoid severe storms by 20 NM.
Mixed check
12 questions pulled from across the unit. Wrong answers explain why and point you back to the lesson.
Explain it to your CFI
Say each one out loud in your own words, in under a minute. If you stall, reread that lesson. This is exactly what an examiner looks for.
- The atmosphere, pressure and wind. Describe the standard atmosphere
- Moisture, stability and clouds. Explain dewpoint and the temperature-dewpoint spread
- Air masses and fronts. Describe the main types of fronts
- Weather hazards: thunderstorms, icing, fog and wind shear. List the ingredients and life cycle of a thunderstorm
What the examiner may ask
What two conditions are needed for structural icing?
Visible moisture and an airframe temperature at or below freezing.
Review: Weather hazards: thunderstorms, icing, fog and wind shear →
Explain mountain and valley winds.
During the day, heated slopes cause upslope (valley) winds; at night, cool air drains downslope into valleys.
What's an occluded front?
Where a faster cold front overtakes a warm front; it can combine both fronts' weather, including embedded thunderstorms.
A cold front is approaching your route. What would you expect?
Possibly a line of thunderstorms or squall line, gusty and shifting winds, turbulence, then clearing and cooler air after passage.