Download Locations of clouds

The clouds
Alessandro Pezzoli, Ph.D.
Sen. Lecturer in Meteo-Hydrology & Weather Risk Management – Politecnico di Torino & Università di Torino (Italy)
Meteorologist (Swedish Sailing Federation, SSF)
6th ÷ 7th February 2016
Understanding Clouds and fog
Clouds are usually the most obvious feature of the sky. They both reflect weather patterns
and play a role in what the weather does. The links below take you to a great deal of
information about clouds.
Locations of clouds
- Low-level clouds: (generally found below 6,500 feet, or 2,000 meters) Low-level clouds
are usually composed of liquid water droplets, but they can have snow and ice crystals in
cold weather
- Mid-level clouds: (generally found between 6,500 and 23,000 feet, or 2,000 and 7,000
meters) Most mid-level clouds are composed of liquid water droplets during summer and a
liquid droplet-ice crystal mix during winter. Mid-level cloud names are preceded by an
"alto" prefix.
- High-level clouds (cirro clouds): (generally found above 20,000 feet, or 6,000 meters)
High-level clouds are composed of ice crystals and tend to be very thin
- Multi-level clouds: Cumulonimbus are the clouds that can produce lightning, thunder,
heavy rains, hail, strong winds, and tornadoes. They are the tallest of all clouds that can span
all cloud layers and extend above 60,000 feet.
1000 m=3281 ft
1 ft=0.305 m
1 m=3.28 ft
12 ÷ 18 km
Cumulus of Fair Weather: Widely separated
heaps with flat bottoms and rounded tops.
Small vertical development
Ground Fog: Layer of stratus lying on the
ground. Forms at night and burns off by
morning
Stratocumulus: A layer of clumps of cloud
with thick and thin areas, often mixed with
cumulus
Nimbostratus: Widespread thick layer of
dark gray cloud producing steady rain
Lightning: Electrical discharge between
cloud and ground, or cloud to cloud, that
occurs in stormy weather cumulonimbus
Virga: Precipitation of ice or water that
evaporates in warmer, drier lower regions
Crepuscular Rays: Open spaces between
clouds allow sun to scatter light in 'dirty' air.
This comes to eye as illusory diverging rays
Stratus: Poorly defined low cloud, usually
with ragged edges
High (Alto) Stratocumulus: Higher layer of
clumpy cloud, sometimes mixed with
Cumulus
Cumulonimbus Shower: Widely separated
showers or squalls of rain, and sometimes
hail, developing in tall cloud
Cumulonimbus (Base and Top): A massive cloud
system with flattish base and top sometimes flattened at
base of the stratosphere. The source of lightning and
thunder, hail, tornados, heavy localized rain showers
Sun Pillar: A beam, or pillar, of sunlight
reflected upward from horizontal surfaces of
hexagonal ice crystals
Cap Cloud: Lenticular cloud that sits on a
mountain peak. Caused by ascending air on
windward side and descending on the lee
side
Billow Altocumulus: Unusual long rolls of
cloud occurring in alto or cirrocumulus due
to shearing motion. Clouds in regions of
ascending air; spaces in regions of
descending air
Swelling cumulus: Separated actively
growing heap clouds with flattish bottoms
and rounded, hard-edged tops
Altostratus: Layer of cloudy air, sometimes
thick and preceding rain. Sun seen as if
shining through ground glass
Altocumulus: Mid-level layered-heap cloud
with many convective cells. Thin regions,
descending air; thick regions, ascending air
Nimbostratus: Widespread thick layer of
gray cloud producing steady snow
Cumulonimbus: Most active member of
cumulus family; flattish base, tops
sometimes extending 5 miles
Corona: Colored ring about moon and sun
due to diffraction of light passing through a
water crystal cloud
Mamma: Layer of cloud with pouch-like
downward extensions, associated with
cumulonimbus in latter stages of
development
"Flying Saucer": Lenticular altocumulus
with remarkable symmetry. Wind blows
through stationary cloud
Cumulus Congestus: An active form of cumulus with
many convective cells yielding cauliflower
appearances to the top. Base is flattish representing
the condensation level. Can produce showers
Cirro stratus: Widespread layer of thin veillike ice crystal cloud. Though it appears thin
it can be deceptively thick
Cirro cumulus: Layered cloud permeated
with small cumuliform lumpiness
Cirrus: Ice crystal clouds in wide variety of
feathery shapes, evaporating as they
precipitate. (A type of virga)
Cumulonimbus (top): Top often resembles a
flattened anvil which sometimes spreads
ahead of main cloud mass. Ice crystal
structure indicated by striations; stringiness
Halo, 22-1/2 degrees: Colored ring about
sun or moon formed as light shines through
cirrostratus ice crystals and experiences
refraction. Interior, red; exterior, violet
Aurora Borealis (Northern Lights): Multi
colored light comes from ionized atoms at
top of the atmosphere in polar regions
Contrail: Cloud formed in wake of jet
aircraft, indicative of upper level humidity
and wind drift. Note vortex twisting motion
Pileus: Fibrous "lid" over cumulus congestus
due to cooling uplift in upper air currents
Thanks for your attention!!!
The clouds
Alessandro Pezzoli, Ph.D.
Sen. Lecturer in Meteo-Hydrology & Weather Risk Management – Politecnico di Torino & Università di Torino (Italy)
Meteorologist (Swedish Sailing Federation, SSF)
6th ÷ 7th February 2016