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ATOC 4720 class20. Clouds and storms 1. Cloud morphology 2. Types of clouds 3. The air-mass thunderstorm. From class-19:. [1]. Thermoelectric effect in ice: T- degree C; V--mV. [2] Supercooled water in clouds. Class-19:. 3. Lightning and thunder.
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ATOC 4720 class20 • Clouds and storms 1. Cloud morphology 2. Types of clouds 3. The air-mass thunderstorm
From class-19: [1] Thermoelectric effect in ice: T- degree C; V--mV [2] Supercooled water in clouds
Class-19: 3. Lightning and thunder Dielectric breakdown: V>3MV/m (dry) V>1MV/m Moist with 1mm in radius; Lightning: T--30,000K; Thunder: Shock waves;
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:
[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
[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. Lee waves can also produce orographic clouds; http://www.faa.gov/and/AC0057/AC0057.HTM
[4] Advection fog: Cooling of air below its dew point due to warm air is Advected to a colder surface.
[5] Arctic sea-smoke (steam fog) Meeting of two parcels of air with different temperatures; both close to be saturated.
[6] Funnel clouds Adiabatic expansion and cooling due to a rapid local Reduction in pressure. Tornadoes or water spouts.
[7] Instabilities (Kelvin-Helmholtz instabilities) Strong wind-shear modify cloud shape;
Types of clouds Many types: (International cloud Atlas) Cumulus: Stratus Cirrus Nimbus (combination) Cirrostratus