Transcript Clouds - Photographing Birds in Flight

AVIATION WEATHER
CLOUDS
CLOUD TYPES
Latin
Root Translation
Cumulus
Stratus
Cirrus
Nimbus
Alto
Pileus
cumulating, heap
layer, straight
curl of hair, horse tail
rain
high
Skull cap
Example
Fair-Weather Cumulus
Altostratus
Cirrus
Nimbostratus
Altocumulus
Smooth tops
High-level clouds=20,000 feet and higher, cirrus, cirrostratus, cirrocumulus
Mid-level clouds=6,500 to 20,000 feet, altostratus, altocumulus, cumulonimbus
Low-level clouds=clouds below 6,500 feet, stratus, stratocumulus
Clouds with vertical development
Cirrus Clouds
thin and wispy
The most common form of high-level clouds are thin and often wispy cirrus clouds.
Typically found at heights greater than 20,000 feet, cirrus clouds
are composed of ice crystals that originate from the freezing of super-cooled
water droplets. Cirrus generally occur in fair weather and point in the direction of
air movement at their elevation.
Cirrostratus Clouds
sheet-like and nearly transparent
Sometimes the only indication of their presence is given by an observed halo around
the sun or moon. Halos result from the refraction of light by the cloud's ice crystals.
Cirrostratus clouds, however, tend to thicken as a warm front approaches, signifying
an increased production of ice crystals. As a result, the halo gradually disappears and
the sun (or moon) becomes less visible.
Altocumulus Clouds
parallel bands or rounded masses
Altocumulus may appear as parallel bands (top photograph) or rounded masses
(bottom photograph). Typically a portion of an altocumulus cloud is shaded, a
characteristic which makes them distinguishable from the high-level cirrocumulus.
Altocumulus clouds usually form by convection in an unstable layer aloft, which may
result from the gradual lifting of air in advance of a cold front. The presence of
altocumulus clouds on a warm and humid summer morning is commonly followed
by thunderstorms later in the day.
Nimbostratus Clouds
dark, low-level clouds with
precipitation
Nimbostratus are dark, low-level clouds accompanied by light to moderately falling
precipitation. Low clouds are primarily composed of water droplets since their
bases generally lie below 6,500 feet. However, when temperatures are cold enough,
these clouds may also contain ice particles and snow.
Stratocumulus Clouds
low, lumpy layer of clouds
Stratocumulus clouds generally appear as a low, lumpy layer of clouds that is
sometimes accompanied by weak intensity precipitation. Stratocumulus vary in
color from dark gray to light gray and may appear as rounded masses,
rolls, etc., with breaks of clear sky in between
Fair Weather Cumulus Clouds
puffy cotton balls floating in the sky
Fair weather cumulus are fueled by buoyant bubbles of air, or thermals, that rise
upward from the earth's surface. As they rise, the water vapor within cools and
condenses forming cloud droplets. Young fair weather cumulus have sharply
defined edges and bases while the edges of older clouds appear more ragged, an
artifact of cloud erosion. Evaporation along the cloud edges cools the surrounding
air, making it heavier and producing sinking motion (or subsidence) outside the
cloud.
Cumulonimbus Clouds
reaching high into the atmosphere
Lower levels of cumulonimbus clouds consist mostly of water droplets while at higher
elevations, where temperatures are well below 0 degrees Celsius, ice crystals
dominate. Under favorable atmospheric conditions, harmless fair weather cumulus
clouds can quickly develop into large cumulonimbus clouds associated with powerful
thunderstorms known as super cells.
Billow Clouds
produced by KelvinHelmholtz instability
Billow clouds are created from instability associated with air flows having marked
vertical shear and weak thermal stratification. The common name for this instability
is Kelvin-Helmholtz instability. These instabilities are often visualized as a row of
horizontal eddies aligned within this layer of vertical shear.
Mammatus Clouds
sagging pouch-like structures
Sometimes very ominous in appearance, mammatus clouds are harmless and do not
mean that a tornado is about to form; a commonly held misconception. In fact,
mammatus are usually seen after the worst of a thunderstorm has passed.
Pileus Clouds
smooth capping clouds
Pileus (Latin for "skullcap") is a smooth cloud found attached to either a mountain
top or growing cumulus tower.
Cloud Type
Effects on Flight
cirrus
no significant icing; turbulence in dense, banded cirrus
cirrocumulus
supercooled water droplets = some turbulence and icing
cirrostratus
little if any icing; no turbulence; restricted visibility
altocumulus
small amounts of icing; some turbulence
altostratus
moderate amounts of icing; little turbulence; restricted sunlight
altocumulus
unstable air; rough turbulence with some icing
lenticular
altocumulus
very strong turbulence
nimbostratus
very little turbulence; can pose serious icing problems if
temperatures are near or below freezing
stratus
little or no turbulence; hazardous icing conditions if
temperatures are near or below freezing. Fog on ground.
stratocumulus
some turbulence; possible icing at subfreezing temperatures;
ceiling and visibility better than with low stratus clouds
cumulus
sunstable air will give some turbulence, but no significant icing
towering
cumulus
strong turbulence,rain showers; clear icing above freezing level
cumulonimbus
unstable air; violent turbulence; strong possibility for icing
CLOUD IDENTIFICATION
TEST
Cirrus
Fair Weather Cumulus
Stratus
Nimbostratus
Stratus
Virga
Towering cumulus
Lenticulars
Fair-weather cumulus
Altocumulus
Cumulonimbus
Stratocumulus
Cumulonimbus
Mammantus
Mammantus
Moon
Altostratus
Scattered stratus
Cumulonimbus
Towering cumulus
Cirrostratus
Altocumulus
Roll cloud
Cumulonimbus
Cirrus
Altocirrus
Cumulus
Altostratus
Stratus
Which way is the wind blowing?
Evening
What time of day is it?
Fair-weather cumulus
Cirrus
Altostratus
Advection fog
Upslope fog
Is there a light wind?
Yes
Which way is it blowing?
Stratocumulus
Stratus
Cumulus
Stratocumulus
Thor
Stratus
Fair-weather cumulus
Tree
Stratocumulus
Stratus
Cumulus
Stratocumulus
Cirrocumulus
Stratocumulus
Stratus
Stratocumulus
Altocumulus and crazy pilot
Stratus
Romantic interlude
Towering cumulus
See the orthographic build-ups on the far side of
the mountain?
Which way is the wind blowing?
What time of day is it?
Afternoon
Stratus
Cumulus
Bristlecone pine – lives longer than 2000 years.
This particular Bristlecone may have been living
during the life of Christ!
Cumulonimbus
Stratus
Towering cumulus
Altostratus
Fair-weather cumulus – looking up from the bottom
Fair-weather cumulus – looking down from the top
Altostratus
Stratus
Cumulus
Crab
Are these Pileus clouds?
Cumulonimbus
Cumulus
Cirrus
Cirrus
Fair-weather cumulus
Altostratus
Be careful! Low-flying military aircraft practice here!
Fair-weather cumulus
Stratocumulus
Altostratus
Cumulus
Cumulonimbus
Cold front
WARM AIR
Alien
COLD AIR
Altostratus
Altocumulus
See the anvil top?
Which way is the storm moving?
Cumulus
Cirrus
Cirrocumulus
Towering cumulus
Stratus
Cumulus
TV antenna
Altocumulus
Cirrus
Altocumulus
Towering cumulus
Stratus
The leading edge of a cold front. Aircraft avoid these things!
Cirrus
What direction is the wind blowing?