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LECTURE 6, Clouds31JAN05

I’ve looked at clouds from both sides now,And still, somehow, I don’t know clouds at all.

Judy Collins

I downloaded these pictures from the following siteshttp://www.cloudman.com/http://www.atmos.washington.edu/atlas/Houze/http://www.photolib.noaa.gov/

Please don’t use them for anything but teaching meteorology at FIUMET 3003, Spring, 2005

How do clouds form?

• Buoyant updrafts in a conditionally unstable atmosphere

• Forced lifting of moist, stable air due to passing weather systems

• Forced lifting as air passes over mountains• Cooling by contact with a cold surface• Mixing of parcels with different temperatures• Adiabatic expansion in tornadoes and waterspouts

How do we classify clouds?

• Cumulus (heaps, puffy, vertical development , water or ice)

• Stratus (Layers, low-level, mostly water)• Alto (-cumulus or -stratus, middle level, water or

ice)• Cirrus (wisps, streaks, high-level, always ice)• Nimbus (raining or snowing)

Proposed by Luke Howard (1803)

Cloud Levels (Etages)

0-2km0-2km0-2kmLow

(St, Sc,Ns)

2-4 km2-7km2-8kmMiddle(As,Ac)

4-8 km5-13 km6-18kmHigh

(Ci,Cs,Cc

PolarTemperateTropicsEtage

Clouds of V

ertical Developm

ent

Cumulus

Stratus

2

Altostratus

Altocumulus

CirrusCumulonimbus

Sea Fog Stratus & Fog

3

Stratus

Stratus

Nimbostratus

Nimbostratus

Stratocumulus

Stratocumulus

4

Stratocumulus Stratocumulus

Stratus & Stratocumulus Altostratus

Altostratus

Altocumulus

5

AltocumulusAltocumulus

Cirrus & Stratocumulus Cirrus

Halos

Cirrostratus

6

Cirrocumulus

Cirrocumulus

Fair Weather Cumulus Towering Cumulus

Cumulus Congestus Entrainment

7

Cumulus Congestus Cumulonimbus

CumulonimbusCumulonimbus &

Pileus

Cb Forming Anvil Various Cumuli

8

CU Growth abcd CU Growth egfh

Orographic CloudsLenticular Clouds

Air-mass convectionCumulonimbus &

Pileus

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FINISFINIS

For more images, visit the FIU on-line Cloud Atlas:http://www.ihrc.fiu.edu/academic_research/courses/hew/cloud_atlas/FIU_Cloud_Atlas_04.html