CLOUDS Flashcards
What gives us an indication that mountain wave in Mountain turbulence exist?
Lenticular clouds
Rotor clouds
Cap clouds
Banner, clouds
Lenticular clouds
Typically occur from 20,000 to 40,000 feet. Form in the crests of the waves, and can be very high and hundreds of miles long.
In PIREPS & METARS lenticular clouds will be reported as one of two types
ACSL
CCSL
Roll/rotor clouds
They will form downwind from each wave crest, and within the lower turbulent zone.
Possess the greatest amount of turbulence.
Can indicate presence of mountain waves
Cap cloud
These lie over the top of the mountain, and they will extend partially down the leeward slopes. This can indicate an extremely strong downdraft.
ACSL
Alto-cumulus, standing lenticular
CCSL
Cirro- cumulus standing lenticular
Winds around mountains
Anabatic winds
Katabatic winds
Glacier winds
Funnel winds
Anabatic winds
Formed as the sun word side of a mountain slope heats up, warm air rises.
Katabatic winds
A wind that flows down the slope of a mountain. It can happen in shaded or snow-covered areas.
Glacier winds
Extreme katabatic winds. They are caused by glaciers which can produce areas of extreme cooling.
Funnelling winds
Winds, which are deflected around large single mountain peaks, or through the valleys of mountain ranges.
When should a light aircraft stay out of the mountains?
When the wind speed at the level of the mountain peak is 20 KT or greater
CB
Low cloud
Cumulonimbus
Thunder and lightning associated. Fueled by vigorous convective updrafts. Tops of these clouds can reach 60,000ft.
TCU
Low cloud
Towering cumulonimbus
Growing cumulus clouds. On the way to becoming a cumulonimbus
CU
Low cloud
Cumulus
Appearance of floating cotton or popcorn popping. Lifetime 5-40mins. Indicates the pressure of significant vertical currents at low levels without precip. With proper conditions they can develop into TCU, And than CB a powerful thunderstorm.
CF
Low cloud
Cumulus Fractus
Stratocumulus torn by wind. Differentiated from stratus Fractus by their more rounded tops.
SC
Low Cloud
Stratocumulus
Low lumpy layer of cloud. Sometimes accompanied by weak intensity precipitation. Main producers of drizzle.
NS
Low cloud
Nimbostratus
Dark low level clouds often accompanied by steady by steady, light to moderate continuous precipitation.
ST
Low Cloud
Stratus
Low layer cloud. Smooth air. Resembles fog but does not rest on the ground. No waves or patterns “grey”
SF
Low cloud
Stratus Fractus
Stratus cloud that has been torn by wind into fragments. Drizzle may fall from these clouds.
AS
Middle cloud
Alto stratus
Low layer cloud with no definite pattern. Steely or bluish in colour. Sometimes sun/moon can be seen through. Can cause light drizzle but NOT heavy precipitation
AC
Middle cloud
Alto cumulus
Puffy cotton ball type clouds
On warm and humid summer morning could be followed by thunderstorms. Icing is usually present above the freezing level, and especially heavy during top on cloud.
ACC
Middle cloud
Alto cumulus Castellanus
Created from instability associated with airflows having marked vertical shear and weak thermal stratification
CI
High cloud
Cirrus
High and wispy, 20,000ft +
High pressure systems, & fair weather, composed of ice crystals
CS
High cloud
Cirrostratus
Sheetlike high level clouds composed of ice crystals. Thicken as warm fronts approach
CC
High cloud
Cirrocumulus
Somewhat rare
Appears as a white sheet with a pebbly pattern
ST
Low clouds
Stratus
Known for drizzle or freezing rain. Updrafts associated with are very weak so the larger droplets in the cloud tend to settle earthward
Mammatus
Powerful cumulonimbus clouds. May have appendages protruding from the base of them. These clouds indicate the atmosphere is extremely unstable. Funnel clouds may also be associated. (Stay clear of these)
CEILING
Is defined as the level of the first cloudbase that has a coverage amount of five to eat octas
