AT620 - Thermodynamics and Cloud Physics

Fall 2016 - Dr. Steven Rutledge

Course Syllabus

Course name:  Thermodynamics and Cloud Physics

Course number:  AT620

Instructor:  Prof. Steven Rutledge, 307 ATS, 970-491-8283.

Instructor web page:

Office hours:  Please email or speak with instructor after class to make an appointment. Special office hours with instructor will be scheduled to students' convenience prior to each exam.

Classroom and meeting time:  101 ATS, 10:00 - 10:50 AM, WF

Prerequisites: Math 340, Physics 142 or permission

Course goals and Objectives:  AT620 is designed to provide a foundational understanding of atmospheric thermodynamics, especially related to nucleation processes.  The course also provides understanding of precipitation processes in clouds, both liquid and ice phases.  Cloud electrification theories are also presented, along with knowledge of the global electrical circuit.  Aerosol sink and sources mechanisms are also discussed.  The objective of the course is to provide the student with a working knowledge of thermodynamics and cloud physics.  

Textbook:  None

Course readings:  As recommended during the semester, also see course web page.  

Course web site:

Course calendar:  Follows CSU course calendar

Expectations:  Regular attendance is strongly recommended.  Read the class notes in advance of class.  

Statement on academic dishonesty:  This course will adhere to the CSU Academic Integrity Policy as found in the General Catalog ( and the Student Conduct Code At a minimum, violations will result in a grading penalty in this course and a report to the Office of Conflict Resolution and Student Conduct Services.

Exam schedule:  To be announced during the semester

Grading policy:  Your course grade will be based on performances on two midterms, a comprehensive final exam and several homework assignments. The midterms will be weighted 25% each towards the course grade. The final will receive a weight of 30%, with the remaining 20% towards the homework assignments.

Contact hours:  Approxomately two hours of effort are expected to complete readings and homework assignments outside of class for each hour of class time.  

TA information:  GTA for this course is Trent Davis (tcd @ TA office hours will be determined at the start of the semester.

Course content:  

I. Thermodynamics 

a. Review and basic concepts: System, state, equilibrium, temperature; energy, work; reversibility; equation of state, properties of mixtures; atmospheric composition.

b. The First Law: Internal energy, heat, enthalpy; heat capacities and calculation of state functions; latent heat, Kirchoff's equation; adiabatic processes, potential temperature.

c. The Second Law: Cyclic processes; entropy, Carnot cycle and the Second Law; generalized statement of the Second Law; Helmholtz and Gibbs functions; thermodynamic potentials; stable and unstable equilibrium; state transitions; enthalpy.

d. Thermodynamics of Moist Air: Phase transitions; Clausius-Clapeyron Equation, geometrical interpretation; chemical potential; heterogeneous systems; equilibrium conditions; Gibbs phase rule; surface tension; equilibrium conditions for systems with curved interfaces, Laplace's equation for mechanical equilibrium.

II. Cloud Physics

a. Nucleation of Droplets: homogeneous nucleation; nucleation on flat insoluble surfaces; nucleation on curved insoluble surfaces; nucleation on water soluble particles.

b. Atmospheric Aerosols: Aerosol sources over land and ocean surfaces, total concentrations; instrumentation for aerosol measurements; size distributions; removal processes.

c. Cloud Condensation Nuclei: Measurement techniques; concentrations over land and ocean surfaces; supersaturation dependence; properties of CCN.

d. Nucleation of Ice: Structure of ice; homogeneous nucleation of ice by freezing and deposition; heterogeneous nucleation of ice on flat and curved surfaces.

e. Ice Nuclei: Mode of action of ice nuclei; measurement techniques; concentrations; sources of ice nuclei; properties of ice nuclei.

f. Droplet Growth Theory: Theory for diffusional growth; growth of a droplet population; evaporation of large drops accounting for ventilation; collision-coalescence growth; stochastic processes; fall mode of large drops; microphysical structure of warm clouds; theories of broadening of cloud droplet spectra by turbulence, inhomogeneous mixing, and ultragiant hygroscopic aerosols.

g. Ice Crystal Growth Mechanisms: Growth from the vapor phase; habit theory; capacitances for various ice crystal geometries; depositional growth rates, effects of ventilation; dimensions of natural crystals, ice crystal fallspeeds; growth by aggregation, growth by riming, formation of hail and growth rate of hailstones (wet and dry regimes); melting of ice particles; ice particle multiplication mechanisms.

h. Atmospheric Electricity: Principles of atmospheric electricity; fair weather electric field, effects of atmospheric pollution; charge generation mechanisms; cloud electrification mechanisms.

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