1. Atmospheric Stability The resistance of the atmosphere to vertical motion. Stable air resists vertical motion Unstable air encourages vertical motion

2. ↓ pressure (expansion) ↑ volume = cooling Air Rising Air Falling ↑ pressure (compression) ↓ volume = warming

3. Dry adiabatic lapse rate (unsaturated air) Lapse rate – change in temperature with elevation Adiabatic process: - No heat is gained or lost by mixing with the surrounding air (“parcels of air”) Dry adiabatic lapse rate = 5.5°F/1000 ft

4. Moist-adiabatic Rate (saturated air) Air rises and cools – if dew point reached, condensation occurs Energy released with condensation → warming Lapse rate reduced to 3°F/1,000 ft Parcel becomes warmer than surrounding air – continues to rise (free convection) Eventually reaches colder air aloft – cools and stabilizes at new level

5. Moist adiabatic lapse rate - May become unstable if air becomes warmer than surrounding area and continues to rise Dry adiabatic lapse rate (stable) - resists vertical motion - parcel will remain in position Inversion Super adiabatic lapse rate - Lapse rate > dry-adiabatic rate - Example: Strong heating of ground surface - Warm air below cool air SOUNDING – Atmospheric Temperature

6. How is air lifted in the atmosphere? Thermal lifting (convection) Orographic lifing Frontal lifting

7. What is the stability of the air?

9. TTYP Read the material independently (2 min) One person explains the material – the other person listens (3 min) The “listener” adds to the explanation any information that they believe would help to improve their understanding of it. (2 min) Both people decide on the best explanation that they both agree with. (2 min) Both should be prepared to share the information with the entire class.

10. Night Inversion

11. Air near Earth’s surface cools at night (radiation, conduction, convection) Cold air flows downward Layer of warm air above = thermal belt Inversions strongest when atmospheric conditions = stable, calm –Clouds & water vapor reduce outgoing radiation –Wind causes air layers to mix Surface heating during day – cause inversion to break = severe fire conditions Night inversion

12. Marine inversion

13. Subsidence Inversion

14. Subsidence & mountain waves (& foehn winds)

15. Signs of a Stable Atmosphere

16. Signs of an Unstable Atmosphere

18. Night Inversion Marine inversion Subsidence Inversion

19. Subsidence & mountain waves (& foehn winds) Signs of a Stable Atmosphere Signs of an Unstable Atmosphere