Cloud Precip Vis And Fog

Question 1

Cloud formation

Answer 1

Saturated air cooled to the point where moisture must be released in the form of condensation
Requires hygroscopic nuclei

Question 2

Cloud layers

Answer 2

High cloud 20000’ to tropopause
Middle cloud 6500’ to 20000’
Low clouds SFC -6500’

Question 3

Orographic lifting

Answer 3

Air travels up and over terrain
Causes mountain waves (multi layered cloud on windward side, lenticular or rotor cloud on leeward side)
Unstable mountain waves look stable but with embedded CB AND TS

Question 4

Slow widespread ascent

Answer 4

Convergence of air spiralling towards centre of low p causing lifting over vast area
All cloud types are likely to be found

Question 5

Mechanical lifting

Answer 5

Air tumbling over obstacles like buildings and terrain
Stable atmos with sufficient lifting can cause stratocumulus
unstable can cause fair weather cumulus to TS depending on instability

Question 6

Convective lifting

Answer 6

Hot SFC warms air above causing it to rise
Can cause fair weather cumulus to TS

Question 7

Water drops

Answer 7

Bigger than cloud drop
Form via cooling
Either freeze and stay in place of fall

Question 8

Buoyancy

Answer 8

Tendency of air parcel to sick or rise due to temperature gradient between surrounding air

Question 9

Cloud drop vs rain drop

Answer 9

Cloud drop 100 micrometer
Raindrops 1-2mm or larger
Cloud drops can only be virga

Question 10

Look at cloud types

Answer 10

Look

Question 11

Precipitation

Answer 11

Liquid or solid water from cloud to ground
Virga does not reach ground

Question 12

Precipitation types

Answer 12

Rain
Drizzle (smaller than rain usually from low stratus cloud)
Snow
Hail frozen balls (associated with CB)
Sleet (rain and snow)

Question 13

Precipitation types (continuous intermittent)

Answer 13

Continuous
Large widespread will not clear soon (Stratiform or nimbostratus)

Intermittent
Continuous from thin layer clouds

Showers
Passing Burt’s from cu type cloud
Light less than 1mm per hour
Mod 1-10mm per hour
Heavy more than 10mm per hour

Question 14

Visibility

Answer 14

Km
Prevailing vis is greatest horizontal vis covering at least half of horizon

Question 15

Rain intensity vis

Answer 15

Light same vis
Mod 3000m-10km vis
Heavy less than 3000m vis

Question 16

Dz or snow intensity vis

Answer 16

Light 8000 m or more
Mod 500-8000m vis
Heavy less than 500m vis

Question 17

Fog mist has smoke vis

Answer 17

Fog <1000m
Mist >= 1000m
Haze smoke <= 5000m

Question 18

Sea spray

Answer 18

Adds water and salt to air via wave movement reduces vis

Question 19

Slant range

Answer 19

Angled view over fog or mist will be more disrupted than too down view as you are looking through more fog or mist

Question 20

RVR

Answer 20

Runway visual range
Horizontal vis along runway from 5m above touchdown point
Used when vis below 1500m