A Quick Introduction to Clouds Lis Cohen [email protected] .
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Transcript of A Quick Introduction to Clouds Lis Cohen [email protected] .
A Quick Introduction to Clouds
Lis Cohen
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 LevelsHigh Clouds
• Generally form above 20,000 feet• Usually appear white, except for sunrise/set• Usually thin and composed almost exclusively
of ice crystals
Cloud LevelsHigh Clouds
Indicative of upper level moisture
(storms possible in 6-24 hours).
Cloud LevelsHigh Clouds
• CIRRUS
• CIRROSTRATUS
• CIRROCUMULUS
Photo: WBZ-Mos
Cloud LevelsMiddle 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 LevelsMiddle Clouds
• ALTOSTRATUS
• ALTOCUMULUS
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 LevelsMiddle Clouds
Cloud LevelsLow 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 LevelsLow Clouds
• Stratus
• Stratocumulus
• Nimbostratus
Museum of Science/WBZ conference
Cloud LevelsLow Clouds
• Can form drizzle like precipitation• Often stable layer is found above these clouds
Cloud LevelsLarge Vertical Development
• CUMULUS
• CUMULONIMBUS
• Cumulus Humulis
• Cumulus Fractus
Cloud LevelsLarge Vertical Development
Photographer: Unknown
Photographer: Unknown
• Cumulus Congestus
• Cumulonimbus Incus
Cloud LevelsLarge Vertical Development
Photographer: Unknown
Photographer: Unknown
• Occurs with an unstable atmosphere
• Often indicative of thunderstorms and heavy rain
Cloud LevelsLarge Vertical Development
Unique Clouds
• Lenticular Clouds
• Pileus Clouds
Photographer: Unknown
Photographer: Jay Shafer
Unique Clouds
• Mammatus Clouds
• Condensation Trail or Contrail
Photographer: Unknown
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