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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
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


3 lightning and thunder

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
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
Types of clouds

Many types: (International cloud Atlas)

Cumulus:

Stratus

Cirrus

Nimbus

(combination) Cirrostratus








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