07/09/2025
Earth Atmosphere
**Definition:** Layers of gases surrounding Earth, affecting flight
**Layers Affecting Flight:**
1. **Troposphere**: 0-12 km - weather, turbulence, icing
2. **Stratosphere**: 12-50 km - stable, jet streams
3. **Mesosphere**: 50-85 km - meteors burn up
4. **Thermosphere**: 85-600 km - aurorae, space weather
**Effects on Flight:**
1. **Air Density**: Decreases with altitude, affects lift and drag
**Definition:** Mass of air per unit volume, affecting aircraft performance
**Factors Affecting Air Density:**
1. **Altitude**: Higher altitude = lower air density
2. **Temperature**: Warmer air = lower air density
3. **Humidity**: Higher humidity = lower air density
**Effects on Aircraft:**
1. **Lift**: Lower air density = less lift, longer takeoff/landing rolls
2. **Drag**: Lower air density = less drag, higher true airspeed
3. **Engine Performance**: Lower air density = less oxygen, reduced power
2. **Temperature Effects
* Temperature variations with altitude affect aircraft performance
**Temperature Lapse Rate:** -6.5°C/km (-3.5°F/1000ft) up to 11km (36,000ft)
**Effects on Aircraft:**
1. **Engine Performance**: Lower temperature = more oxygen, more power
2. **Air Density**: Lower temperature = higher air density, more lift/drag
3. **Icing**: Freezing temperatures = icing risk on wings and engines
3. **Wind**: Jet streams, turbulence affect route planning
**Definition:** Wind and jetstreams significantly impact aircraft flight
**Jetstream Characteristics:**
1. **Altitude**: Typically 7-12 km (23,000-39,000 ft)
2. **Speed**: Up to 400 km/h (250 mph)
3. **Direction**: Generally west-to-east
**Effects on Aircraft:**
1. **Headwinds**: Increase flight time, reduce groundspeed
2. **Tailwinds**: Decrease flight time, increase groundspeed
3. **Crosswinds**: Affect navigation, require course corrections
4. **Turbulence**: Associated with jetstream edges and mountain waves