This document discusses various types of clouds and precipitation. It describes how temperature changes can cause air to expand and cool through adiabatic processes. Different lifting mechanisms like orographic lifting and convergence can cause air to rise and form clouds. Clouds are classified by height into high, middle, and low clouds and by form. Precipitation occurs through collision-coalescence in warm clouds and the Bergeron process in cold clouds. Rain, snow, sleet, glaze and hail are also explained.

1. By Brianna Shevlin

2. Adiabatic Temperature Changes
and Expansion and Cooling
 Temperature changes, even without
adding or subtracting heat is called
adiabatic temperature changes.
 When air expands, it cools and when
compressed, it warms.
 Moving upward the air expands and
cools due to passing regions of low
pressure.
 Cooling generates clouds and
precipitation
kidsgeo.com
 Unsaturated air cools at 10 degrees
Celsius every 1000 meters upward.

3. Orographic Lifting
 Elevated land, like mountains, that blocks air flow
proves orographic lifting is occuring.
 More rain occurs on the windward side.
 An example is the Great Basin Desert is cut off by the
Sierra Nevada Mountains.
examiner.com

4. Frontal Wedging
 Warm air colliding with cool air produces a front.
 Cool dense air is a barrier to the warm air that rises.
geo.hunter.cuny.edu

5. Convergence
 When air in the lower atmosphere flows together,
lifting occurs. This is called convergence.
 Air flows from more then one direction and when it
can’t go down, it goes up.
 Convergence causes clouds and precipitation.
ww2010.atmos.uiuc.edu

6. Localized Collective Lifting
 Unequal heating of Earth’s surface
may cause pockets of air to be
warmer then the surrounding air.
 Rising parcels of warm air are called
thermals.
 Process that makes parcels is
localized collective lifting.
 Parcels that rise above condensation
richhoffmanclass.com
level results in the formation of
clouds and possible rain showers.

7. Stability
 Stability is when the air is cooler then its
surroundings.
 Air is dense and sinks to original position
resisting vertical movement.
Difference: presstv.ir
 Stable air remains in the same position while
unstable air rises.
Stability and Daily Weather:
 Stable air is forced upward by other processes
 Clouds are widespread and have little vertical
thickness.
 Lifting of unstable air results in thunder
storms and possible tornados.
 On overcast, dreary days stable air has been
forced up
 Puffy clouds means unstable air rose.

8. Condensation
 Happens when water vapor in the
air changes to a liquid.
 Forms dew, fog, or clouds.
 Must be at a surface for the water
vapor to condense on.
 Clouds occur when water vapor uses weatherquestions.com
condensation nuclei as its surface.

9. Types of Clouds
 Clouds are classified based on
form and height.
Cirrus: High, white, and thin.
Cumulus: Rounded and
individuals.
eo.ucar.edu
Stratus: Sheets cover most or all of
the sky. There are no individual
clouds.
 Three levels of clouds: high,
middle, and low.

10. High Clouds
 Bases are above 6000 meters.
 Cirrocumulus:
 fluffy.
 Cirrostratus : eo.ucar.edu
 flat layer, thin, white, and made up of ice crystals.
 Due to low temperature (the higher, the cooler) and
the small amount of water vapor there is no rain.
 High clouds show warning of stormy weather

11. Middle Clouds
 Bases are 2000-6000 meters high.
 Altocumulous:
 rounded, large, and dense.
 Altostratus:
 White or gray sheet that covers the sky. Produce light
snow drizzle.
bigbranch.net

12. Low Clouds
 Bases are 2000 meters or below.
 Stratus:
 Foggy layer that covers the sky
 Produce occasional precipitation
eo.ucar.edu
 Stratocumulous:
 appear in patches
 Develop at the bottom of a stratus cloud.
 Nimbostratus:
 They are the most common precipitation makers
 They form during stable conditions
 It’s a rainy cloud that covers the sky.

13. Clouds of Vertical Development
 Some clouds don’t fit into the
three categories.
 Their base is at a low range
but extend upward into the
middle and higher range.
 Due to unstable air.
 One cloud is called
cumulonimbus which causes
rain and thunderstorms.
 Cumulus clouds fit in this
category. bigbranch.net

14. brainharmonycenter.com
Fog
Fog:
 Clouds with bases near the ground.
 Happens due to radiation cooling or movement or air over a cool
surface.
Cooling:
 Cools rapidly by radiation on cool, clear nights.
 A thin layer of air near the ground is cooled below dewpoint.
 Air cools and becomes dense, draining into low areas.
Evaporation:
 There is a steaming appearance.
 When cool air is over warm water there may be enough moisture
to evaporate and produce saturation
 Increase in water vapor.

15. Cold Cloud Precipitation
 Bergeron process relies on two
processes: supercooling and
supersaturation.
 Water below 0 degrees Celcuis is
supercooled.
 Ice crystals grow as cloud droplets
do, when they are big enough they
will fall.
 When the surface temperature is
rst.gsfc.nasa.gov
above 4 degrees Celcuis,
snowflakes will melt before
reaching the ground.

16. Warm Cloud Precipitation
 In warm clouds, the formation of raindrops is called
collision-coalescence process.
 Water absorbing particles remove water vapor from air
at relative humidity's less than 100% forming large
drops that collide and join with smaller, slower
droplets
apollo.lsc.vsc.edu

17. Rain and Snow
 Rain means drops of water that fall
from a cloud.
 Small drops are called a drizzle.
 Snow turns to rain before even
hitting the ground when the surface roymiller.hubpages.com
temperature is above 4 degrees
celcuis.
 At low temperatures, light, fluffy
snow made of ice crystals form.
 At temperatures warmer than 5
degrees celcuis,I ice crystals are
larger clumps.
itunes.apple.com

18. wunderground.com
Sleet, Glaze, and Hail
Sleet:
 The fall of small particles of clear ice.
 Forms when a layer of air with temperatures
above freezing over lay a subfreezing layer near
the ground. sercc.com
Glaze:
 Freezing rain
 Happens when raindrops become supercooled.
 Turn solid when impacting objects.
Hail:
 Produces in cumulonimbus clouds.
rufinope.comlu.com
 Small ice pelets grow by collection of
 supercooeld water droplets as they fall through
clouds.

19. Bri’s Presentation on
Clouds and
Precipitation!
The End!