1. Clouds and Precipitation
By: Alaina Klee
http://www.wpclipart.com/weather/rain_water/rain_cloud_BW.png.html
2. Adiabatic Temperature Changes and
Expansion and Cooling
• Temperature changes
that happen even
though heat isn't added
or subtracted
• When air expands it
cools, and when it is
compressed it heats up
• As air moves up into the
atmosphere it expands
and cools
http://www.kidsgeo.com/geography-for-
kids/0070-adiabatic-temperature-changes.php
3. Orographic Lifting
• When elevated land acts
as a barrier to air flow
• As the air goes up,
adiabatic cooling usually
occur and causes clouds
and precipitation
• By the time air gets to the http://www.myoops.org/twocw/usu/Fores
t__Range__and_Wildlife_Sciences/Wildlan
leeward side of a d_Fire_Management_and_Planning/Unit_
mountain , most of the air 7__Atmospheric_Stability_and_Instability_
3.html
moisture is gone.
4. Frontal Wedging
• Warm and Cold air
collide making a front.
• Cooler/denser air is a
wall to warm air, the
warm air rises.
• Another way to lift air
http://www.geography.hunter.cuny.edu/~tbw/
wc.notes/4.moisture.atm.stability/frontal_wed
ging.htm
5. Convergence
• this is where the air that
flows in more than one
direction goes.
• lifting is the result of air in
the lower atmosphere
flowing together. http://www.panoramio.com/photo/195
• Air flow from the ocean 11021
along the coast leads to a
pileup of air and general
convergence over the
peninsula.
6. Localized Convective Lifting
• unequal heating can
cause pockets of air to be
warmed more than the
surrounding air on the
Earth’s surface.
• thermals are the rising
parcels of warmer air. http://wps.prenhall.com/esm_lutgens_fo
undations_4e/47/12104/3098876.cw/co
• humans use these ntent/index.html
thermals for hang gliding
and birds use it to soar
through the sky with
ease.
7. Stability (Density Differences & Stability
and daily weather)
• unstable air tends to rise,
while stable air tends to
remain in its original
position.
• expansion can cause the
volume of air that is
forced to rise, to have a
drop in temperature.
• When stable air resists
vertical movement it
causes unstable air to rise
freely.
8. Condensation
• When water vapor in
the air changes to a
liquid.
• Many times it will either
be in the form of fog,
dew, or clouds.
• This only occurs if air is
http://www.signsoflightstore.net/newgallerym
saturated aker14STORE.php?mytitle=interesting
9. Types of clouds
• Cirrus clouds appear as
patches or as feather-
like wispy fibers.
• Cumulus clouds appear
to look like rising domes
or towers.
• Stratus clouds tend to
look like sheets or layers
that cover most of the
sky.
http://en.wikipedia.org/wiki/File:Clouds.JPG
10. High Clouds
• Cirrus, cirrocumulus, and
cirrostratus make up
these clouds.
• The cirrocumulus clouds
are fluffy, while the
cirrostratus clouds are flat
layers.
• Often made up of ice
crystals because of low
temperatures and small http://www.bigbranch.net/high%20clouds.htm
quantities of water vapor
present at high altitudes
11. Middle Clouds
• These are also known as
altocumulus clouds.
• They also have larger,
denser, rounded masses
compared to
cirrocumulus clouds.
• Are a uniform white to
grayish sheet covering
http://www.bigbranch.net/middle%20clouds.h
the sky with the sun or tm
moon visible as a bright
spot.
12. Low Clouds
• Stratus, stratocumulus,
and nimbostratus are
what make up these
clouds.
• Rarely do these clouds
have precipitation and if
they do it’s a light
amount.
http://patschilling.com/pages/otherlandscapes
• Nimbostratus clouds .html
are the main producers
of precipitation
13. Clouds of Vertical Development
• Clouds that don’t fit into
any of the three height
categories.
• The bases are normally in
the low height range but
can extend upward into
the middle or high
altitudes.
• These are clouds that
grow dramatically under http://thestormking.com/tahoe_nuggets/Nugg
the proper circumstances et_87/nugget_87.html
14. Fog (by cooling and by evaporation)
• Appearance wise, there is
no difference between a
fog and a cloud.
• The only difference
between them is the
method and place of
formation.
• Generally the result of
radiation cooling or the
movement of air over a
cold surface. http://lupusincolor.blogspot.com/2011/01/lup
us-fog.html
15. Cold Cloud Precipitation (Bergeron
process)
• Relies on two physical
processes: supercooling
and supersaturation
• Pure water suspended in
the air isn’t supercooled
until it has reached 0°C
• When the air appears to
be supersaturated to the
http://www.atmo.arizona.edu/students/c
ice crystals, the ice ourselinks/spring07/nats101s2/lecture_n
crystals can’t coexist with otes/mar30.html
water droplets.
16. Warm Cloud Precipitation (collision-
coalescence process)
• Clouds located well below
the freezing level may
have plenty of rainfall.
• The collision-coalescence
process is the mechanism
that forms raindrops in
warm clouds.
• Water vapor can be
removed from the air at
relative humidities less http://claremont327.blogspot.com/2009/11/cl
ouds-and-precipitation.html
than 100 percent with
water-absorbing particles.
17. Rain and Snow
• Rain is drops of water
that fall from a cloud.
• Snowflakes melt and
continue their descent
as rain before they
reach the ground.
• Light, fluffy snow made
up of individual ice
crystals form when http://snowpictures.net/Snow-
storm.html
there are low
temperatures in the air.
18. Sleet, Glaze and Hail
• The fall of small
particles of clear-to-
translucent ice, known
as sleet.
• Freezing rain or the
result of raindrops
http://www.waterencyclopedia.com/Ce-
becoming supercooled, Cr/Climate-Moderator-Water-as-a.html
known as glaze.
• Cumulonimbus clouds
are produced by hail.
