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

ATOC 4720 class20

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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. - PowerPoint PPT Presentation

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Page 1: ATOC 4720 class20

• Clouds and storms

1. Cloud morphology

2. Types of clouds

3. The air-mass thunderstorm

ATOC 4720 class20

Page 2: ATOC 4720 class20

Thermoelectric effect in ice:

T- degree C; V--mV

From class-19:

[1]

[2] Supercooled water in clouds

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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;

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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:

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[2] Layer clouds: stratus

Forced lifting of stable air:

Examples: fog is forced lifted upwards; cold fronts lift warm air massHundres--thousands km; Lifting rates: a few cm/s;Water: a few tens

Tens of hours

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stratus

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[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;

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Orographic clouds

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[4] Advection fog:

Cooling of air below its dew point due to warm air is Advected to a colder surface.

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Fog

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

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Arctic sea-smoke

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[6] Funnel clouds

Adiabatic expansion and cooling due to a rapid local Reduction in pressure.

Tornadoes or water spouts.

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Funnel clouds

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Funnel clouds

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[7] Instabilities (Kelvin-Helmholtz instabilities)

Strong wind-shear modify cloud shape;

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Billow clouds: K-H instability

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Types of clouds

Many types: (International cloud Atlas)

Cumulus: StratusCirrusNimbus(combination) Cirrostratus

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Cumulus

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Cumulus tower

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Cumulonimbus

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Stratus

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Cirrus clouds

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Cirrostratus: halos