Transcript Clouds and Precipitation - Mr. Tobin`s Earth Science Class

April 15, 2014
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Students will be able to explain the
difference between stable and unstable
air.
Students will be able to compare and
contrast low, middle, high and vertical
development clouds.
Students will be able to explain how
precipitation forms.
 Condensation: The
process in which
water vapor changes to a liquid.
 P. 297
 Main
Idea: Clouds vary in shape,
size, height of formation, and
type of precipitation.
 P. 297
 Cloud
Formation:
• Clouds form when rising air masses
cool.
• Cooling causes water vapor to
condense.
 P. 297
 Condensation
Nucleus: A particle
in the atmosphere around which
water droplets can form.
• Ice
• Salt
• Dust
 Droplets
can be ice or water.
 When there are a lot of droplets,
clouds are visible.
 P. 298
 Atmospheric
Stability: As an air
mass rises it cools.
• Stable Air: Air that stops rising
because it has cooled.
 Produces fair weather clouds.
• Unstable Air: Air that continues to
rise because it is always less dense
than the surrounding atmosphere.
 Produces thunderstorm clouds.
 P. 299
 Atmospheric Lifting:
• Clouds form when moist air rises and
cools.
• Convective Lifting:Warm, less dense air
will rise.
• Orographic Lifting: When an air mass is
forced to rise over a topographic barrier
(mountains.)
 Wind forces warm air up mountain side.
 When air reaches dew point, clouds form
and precipitation occurs.
• Convergence: Warm air collides with cold
air.
 Less dense warm air is forced up.
 When rising air reaches dew point clouds
form.
 P. 300
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Types of Clouds:
Classification of clouds based
on 2 things:
Altitude
Shape
 P. 300
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3 Classes of Clouds based on
Altitude:
Low - below 2000m
Middle - between 2000m and
6000m
High - above 6000m
 P. 300
Low:
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Cumulous: Puffy and lumpy looking
Stratus: Layered, sheetlike, block whole sky.
Middle:
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Ice and water droplets
Altocumulous: White or gray - Large round or
wavy
Altostratus: Gray - Thin sheets
High:
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Ice crystals
Cirrus: Whispy and indistinct
Cirrostratus: Continuous layer that covers the
sky
 P. 301
Vertical Development Clouds:
Rising unstable air
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Cumulonimbus: Tall, Ice at top
 May produce rains, winds and hail
 Associated with thunderstorms