Section 5.4 Gravity Waves

1. Section 5.4 Gravity Waves

2. Gravity Waves • Gravity acts as the restoring force on parcels displaced from hydrostatic equilibrium. • Pure gravity exists when the fluid is stably stratified. • Two types of gravity waves: • external gravity waves: static stability is due to the density discontinuity at the interface between two fluids • internal gravity waves: static stability arises from the stable stratification, buoyancy force acts as the restoring force

3. External Gravity Waves: Density Discontinuity Air: Small Density h’ h’ Water: Large Density

4. Transverse Waves: Waves are oscillations (in field variables, such as velocity or pressure) that propagate in space.

5. Surface (External) Gravity Waves

6. Tsunami: Shallow Water Waves

7. Gravity Waves • Gravity acts as the restoring force on parcels displaced from hydrostatic equilibrium. • Pure gravity exists when the fluid is stably stratified. • Two types of gravity waves: • external gravity waves: static stability is due to the density discontinuity at the interface between two fluids • internal gravity waves: static stability arises from the stable stratification, buoyancy force acts as the restoring force

8. Internal Gravity Waves: Stable Stratification Colder than the env.; Downward acc. Warmer than the env.; Upward acc.

9. Vertical Velocity (w) Field During a Model Initial Adjustment Periods

10. Internal Gravity Waves Generated by Rapidly Rising Deep Convection

11. Mountain Waves and Clouds

12. Lenticular Cloud