1. Clouds and storms 1. Cloud morphology 2. Types of clouds 3. The air-mass thunderstorm ATOC 4720 class20

2. Thermoelectric effect in ice: T- degree C; V--mV From class-19: [1] [2] Supercooled water in clouds

3. 3. Lightning and thunder Dielectric breakdown: V>3MV/m (dry) V>1MV/m Moist with 1mm in radius; Class-19: Lightning: T--30,000K; Thunder: Shock waves;

4. 1. Cloud morphology Clouds: Mechanisms of formation [1] Convective clouds: local ascent of warm, conditionally unstable air; 0.1-10km in diameters; Vertical velocity w: a few m/s; Liquid water or ice content:

6. [2] Layer clouds: stratus Forced lifting of stable air: Examples: fog is forced lifted upwards; cold fronts lift warm air mass Hundres--thousands km; Lifting rates: a few cm/s; Water: a few tens Tens of hours

7. stratus

8. [3] Orographic clouds Forced lifting of air by hills or mountains Uplifting velocity depends on windspeed and direction, And mountain height. Can be a few m/s; Water: a few tens Can be transitory, or can stay for long if winds are Steady. http://www.faa.gov/and/AC0057/AC0057.HTM Lee waves can also produce orographic clouds;

9. Orographic clouds

10. [4] Advection fog: Cooling of air below its dew point due to warm air is Advected to a colder surface.

11. Fog

12. [5] Arctic sea-smoke (steam fog) Meeting of two parcels of air with different temperatures; both close to be saturated.

13. Arctic sea-smoke

14. [6] Funnel clouds Adiabatic expansion and cooling due to a rapid local Reduction in pressure. Tornadoes or water spouts.

15. Funnel clouds

17. [7] Instabilities (Kelvin-Helmholtz instabilities) Strong wind-shear modify cloud shape;

18. Billow clouds: K-H instability

19. Types of clouds Many types: (International cloud Atlas) Cumulus: Stratus Cirrus Nimbus (combination) Cirrostratus

20. Cumulus

21. Cumulus tower

22. Cumulonimbus

23. Stratus

24. Cirrus clouds

25. Cirrostratus: halos