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Lecture 9

# ATMO 201 Lecture Notes - Lecture 9: Shortwave Radiation, Fluid Parcel, Advection

Department
Atmospheric Sciences
Course Code
ATMO 201
Professor
Timothy Logan
Lecture
9

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Lecture 9
Tuesday, February 21, 2017
3:56 PM
Chapter 5 - Clouds and Stability
Cumulus = unstable atmosphere
Atmospheric Stability
Equilibrium - a steady state condition where one state is constantly
converted back to an original state or to another state
o Sometimes reversible, sometimes not; depends on the condition
o Sun comes up = heats earth (shortwave radiation) and then sun goes
o Boulder picture - man has a boulder and pushes it up a hill, but it comes
back to the bottom THIS IS STABLE EQUILIBRIUM
o Stable - you always come back to the same stage
Man gets to the top of the hill and pushes it down the other side
THIS IS UNSTABLE EQUILIBRIUM
o Metastable Equilibrium - the sun rises (unstable), sun sets (stable) but
the atmosphere is never the same but the sun rising and setting is the
same AKA REAL LIFE
Parcel Theory
Assume bundles of air in a "thin, elastic wrap"
Adiabatic - no heat exchange with surroundings or mass
o dH=0 (Change in h=0)
o Parcel and surroundings can do work on each other
o dW does not equal 0 (change in w does not = 0)
Recall: pressure and temperature decrease with height
What happens to the parcel as it rises or sinks?