Transcript A Quick Introduction to Clouds

A Quick Introduction to Clouds
Lis Cohen
[email protected]
www.WeatherOutreach.org
Cloud Naming
• Cloud naming is based
on four cloud
characteristics and
three cloud levels
• There are about 30
distinct cloud types
• Professionals may use
10, a casual observer 3
or 4
Cloud Characteristics
• Cirrus
– Fiber or Hair
• Cumulus
– Heaped or Piled
Cloud Characteristics
• Stratus
– Sheet or Layer
• Nimbus
– Rain Making
Cloud Levels
• High Cumulus
– Size of top of thumb
at arms length
• Low Cumulus
– Size of fist at arms length
Photo: WBZ-Mos
Cloud Levels
• High Stratus
– Sun and Moon easily seen
• Low Stratus
– Sun and Moon difficult to see
Cloud Levels
High Clouds
• Generally form above 20,000 feet
• Usually appear white, except for sunrise/set
• Usually thin and composed almost
exclusively
of ice crystals
Cloud Levels
High Clouds
Indicative of upper level moisture
(storms possible in 6-24 hours).
Cloud Levels
High Clouds
• CIRRUS
• CIRROSTRATUS
• CIRROCUMULUS
Photo: WBZ-Mos
Cloud Levels
Middle Clouds
• Cloud bases are located between
6,500-23,000 feet in the mid-latitudes
• Composed of water droplets and when
temperatures are low enough, some ice
crystals
Cloud Levels
Middle Clouds
• ALTOSTRATUS
• ALTOCUMULUS
Cloud Levels
Middle Clouds
ALTOCUMULUS
Possible marker of PM t-storms when seen in the AM
with greater vertical development.
(Clouds form in unstable air with stable air above them.)
Cloud Levels
Low Clouds
• Cloud base lies below 6,500 feet
• Almost always composed of water droplets,
but in cold weather, may contain ice particles
and snow
Cloud Levels
Low Clouds
• Stratus
• Stratocumulus
• Nimbostratus
Museum of Science/WBZ conference
Cloud Levels
Low Clouds
• Can form drizzle like precipitation
• Often stable layer is found above these
clouds
Cloud Levels
Large Vertical Development
• CUMULUS
• CUMULONIMBUS
Cloud Levels
Large Vertical Development
• Cumulus Humulis
Photographer: Unknown
• Cumulus Fractus
Photographer: Unknown
Cloud Levels
Large Vertical Development
• Cumulus
Congestus
Photographer: Unknown
• Cumulonimbus
Incus
Photographer: Unknown
Cloud Levels
Large Vertical Development
• Occurs with an
unstable atmosphere
• Often indicative of
thunderstorms and
heavy rain
Unique Clouds
• Lenticular Clouds
Photographer: Jay Shafer
Photographer: Unknown
• Pileus Clouds
Unique Clouds
• Mammatus Clouds
• Condensation Trail
or Contrail
Common Cloud Types
Description of Sky Conditions
• SUNNY OR CLEAR
less than 1/10 sky
covered by clouds
• PARTLY CLOUDY/
PARTLY SUNNY
1/10 to 5/10 of sky is
covered by clouds
Description of Sky
Conditions
• MOSTLY CLOUDY
(MOSTLY SUNNY)
6/10 to 9/10 of sky
is covered by clouds
(sun)
• OVERCAST
more than 9/10 of the sky
is covered in clouds
Undercast
Cloud Naming