Physical GeographyLecture 23
Buoyancy, Stability, Clouds and Fog
A visible collection of microscopic liquid water droplets and/or ice crystals
Clouds
Adiabatic Cooling of Rising Air Condensation and/or Deposition Need something to condense or deposit
upon: ◦ Condensation Nuclei◦ Freezing Nuclei
Formation of Clouds
Cloud Forms
◦ Stratus clouds
◦ Cumulus clouds
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Figure 6-15b
Figure 6-15c
Cloud Heights
◦ High clouds (> 6 km)
◦ Middle clouds (2 - 6 km)
◦ Low clouds (<2 km)
◦ Clouds of vertical development Can grow up from low
bases to>15 km
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Figure 6-16
Cirrus (Mare’s Tails)
Altocumulus Altostratus
Atmospheric Stability and Buoyancy
Adiabatic Cooling
Lifting Condensation Level
Stable Air and Cloud Formation
Unstable Air + Cloud Formation
Conditional Instability
Radiation Fogcool, clear, calm nights
Valley Fog – a type of radiation fog
Steam or Evaporation Fog