Download Clouds

Clouds
• Identify cloud types from photos
• Recognize and define prefixes and
suffixes for cloud types
• Associate general weather conditions with
cloud types
• Describe different fog types
Clouds
Click on the image to access the Main Cloud Type image search page
Click on the image to access the NOAA Cloud Chart
Three kinds of fog
• Radiation fog
• Advection fog
• Evaporation fog
Evaporation fog on the Kentucky River
Precipitation
• Explain the collision coalescence process and
the Bergeron process
• Describe the basic role naturally occurring
atmospheric aerosols play in precipitation
formation
• Explain how supersaturated atmospheric
conditions develop
• Describe how air pollution impacts cloud
formation and precipitation
• Explain the logic behind weather modification
• Collision coalescence
process of precipitation
formation
– Water droplets collide
and increase in size
until large enough for
gravity to pull them out
of the cloud
– Occurs in tropics and
warmer midlatitudes
– Precip leaves cloud as
liquid water
• Collision coalescence
process requires
presence of
condensation nuclei
– In clean air, RH must
equal 120% for
condensation to occur
– Air would be considered
supersaturated with water
vapor
– Presence of condensation
nuclei allows condensation
at 100% humidity
http://www.youtube.com/watch?v=E8AvfXar9zs
• Bergeron process of
precipitation formation
– Occurs in midlatitudes to
poles
– All three states of water
present
– Supercooled water
crystallizes upon contact with
freezing nuclei
– Ice crystals form around
freezing nuclei and grow
through deposition at the
expense of water droplets
– Precipitation leaves cloud as
ice crystal
Precipitation types under
Bergeron conditions
• Rain – ice crystal melts and liquid water reaches
surface
• Sleet – warm layer melts ice but refreezes as
“pellet”. Winter phenomena.
• Snow – ice crystal falls to ground intact
• Freezing rain – supercooled liquid water freezes at
surface
• Hail – summertime thunderstorm phenomena.
Conditions for frozen precipitation in
KY/Upper South/Lower OH Valley
Midlatitude cyclones
Life cycle of midlatitude cyclone
Sleet profile
Snow temperature profile
Freezing rain profile
Where the low pressure center of the mid latitude cyclone tracks determines the
atmospheric temperature profile and whether or not Lexington or another
location gets snow, wintery mix (sleet or freezing rain), or rain.
Draw a profile for rain
Aerosol air
pollution,
clouds, and
precipitation
Albedo greater in
polluted
atmosphere
Clouds last longer
in polluted
atmosphere