This document discusses various atmospheric processes that lead to cloud formation and precipitation. It covers topics like adiabatic cooling and warming, orographic and frontal lifting, convection, stability, condensation, different cloud types based on altitude, precipitation processes like the Bergeron process and collision-coalescence, and types of precipitation including rain, snow, sleet, glaze and hail. The document provides information on the mechanisms and conditions required for various cloud and precipitation formation.

1. By Josh Pfleger

2. Adiabatic Temperature Changes and
Expansion and Cooling
Temperatures that happen even when heat isn't
added or subtracted.
Its caused when air is compressed or able to
expand. When air is able to expand it cools, when
its compressed it warms.

3. Orographic Lifting
• Elevated terrains act as barriers to air flow.
• As air goes up a slope or mountain, adiabatic
cooling often generates clouds and
precipitation.
• As air reaches the leeward side of a mountain,
most of its moisture has been lost.

4. Frontal Wedging
• In Central North America, warm air and cool
air collide producing a front.
• The cooler, denser air acts as a barrier over
which warm less dense air rises which is called
frontal wedging.

5. Convergence
• Lifting air in the lower atmosphere is called
convergence.
• When air flows in from more then one
direction it must go somewhere, because it
can’t go down, it has to go up.

6. Localized Convective Lifting
• On summer days, unequal heating of Earth’s
surface may cause pockets of air to be
warmed more than the surrounding air.
• Rising air of parcels are called thermals
• The process that produces rising thermals is
localized convective lifting.

7. Stability
• If a volume of air was forced to rise, its
temperature would drop because of expansion.
• Stable air tends to remain in its first position,
while unstable air tends to rise
• Air stability is determined by measuring the
temperature of the atmosphere at various
heights
• Because stable air resists upward movement, you
might conclude that clouds wont form when
stable conditions are present in the air.

8. Condensation
• Condensation happens when water vapor in
the air changes to a liquid.
• Examples of condensation could be dew, fog
or clouds.
• Air must be saturated for these forms to
happen.

9. Types of clouds
• Three basic types are cirrus, cumulus and
stratus
• Cirrus clouds are high, white and very thin.
• Cumulus clouds consist of rounded individual
cloud masses.
• Stratus clouds are sheets or layers the cover
much or all of the sky.

10. High clouds
• The three high clouds are cirrus, cirrostratus
and cirrocumulus.
• All high clouds are thin and white
• These clouds are not considered precipitation
makers

11. Middle clouds
• Altocumulus clouds are composed of rounded
masses that differ from cirrocumulus clouds.
• Clouds that appear in the middle range, from
2000 to 6000 meters, have the prefix alto, as
part of there name.

12. Low clouds
• The three low clouds are stratus,
stratocumulus and nimbostratus.
• Stratus clouds are fog like layer of clouds that
frequently cover the sky.
• Occasionally these clouds might produce light
precipitation.

13. Clouds of vertical development.
• Some clouds do not fit into any one of the
three height categories mentioned.
• Cumulus clouds may grow dramatically under
the proper circumstances
• The result often is cumulonimbus cloud that
may produce rain showers or a thunderstorm

14. Fog
• Physically there is no difference between fog and
a cloud. The only difference is the method and
place of formation.
• Most fog is a result of radiation cooling or the
movement of air over a cold surface.
• A blanket of fog is produced in some West Coast
locations when warm, moist air from the pacific
ocean moves of the cold California current then is
carried onshore by prevailing winds

15. Cold Cloud Precipitation
• The Bergeron process relies on 2 physical
processes, which are supercooling and
supersaturation.
• Cloud droplets do not freeze at 0 degrees
Celsius as expected
• Supercooled water will readily freeze If it
impacts a solid object.

16. Warm Cloud Precipitation
• In warm clouds, the mechanism that forms
raindrops is the collision coalescence process
• A lot of the rainfall can be connected with
clouds located below freezing level especially
in the tropics
• As large droplets move through the cloud,
they collide and join together with smaller
slower droplets

17. Rain and Snow
• The term rain means drops of water that fall from
a cloud and have a diameter of at least 0.5
millimeters.
• When surface temperature is above four degrees
Celsius, snowflakes usually melt and continue
their descent as rain before it reaches the
ground.
• At temperatures warmer than negative five
degrees Celsius, ice crystals join into larger
clumps

18. Sleet, Glaze and Hail
• Sleet is the fall of small particles of clear to
translucent ice.
• Glaze results when raindrops become
supercooled as they fall through subfreezing
air near they ground and turn to ice when
they impact the object
• Hail is produced in cumulonimbus clouds

19. THE END