67111 - Planetary Atmospheres

Learning outcomes

At the end of the course the Student is able to analyze the planetary atmospheres as physical systems. He learns the phenomenology and equations governing the fundamental physical processes occurring in the planetary atmospheres. The Student is able to interpret simplemodels ofgreenhouse effect and to link climatic patterns with orbital parameters of Planets.

Course contents

1) Introduction What is a planet and why a planet is round and smooth. The planets of the solar system. 

2) Origin and composition of the Solar System Cosmogonic theories, the nebular theory. Physical features of the porto-planetary nebula. Angular momentum conservation. The accretion theory. Oort cloud and kuiper belt. Satellites and rings, the Roche limit. Minor bodies of the solar system: nanoplanets, asteorids, comets, meteorits. Transneptunian objects. Origin of the moon.

3) Main characteristics of the Earth and Planets atmosphere Composition and chemical evolution: secondary atmosphere. Mass escape mechanisms (Jeans Escape). Mean thermal structure. The Stratosphere and the role of the Ozone layer. Thermal vertical profile of internal and external planets and Titan.

4)  Thermodynamics of the Atmosphere Air parcel concept. The gas laws applied to the real atmospheres. Hydrostatic balance and hypsometric equation. Dry air: adiabatic processes and lapse rate. Diabatic processes and diabatic stratification. 

5) Hydrostatic Stability Buoyancy force and vertical velocities. Static stability and the Brunt Vaisala frequency. Categories of static stability for dry air and convection. Auto-convective gradient.   

6) Water Vapour and Condensed Phases in the Atmosphere Water vapour saturation pressure and phase changes. Adiabatic lapse rate for saturated air (pseudo-adiabats). Condensed states in atmospheric planets: clouds and hazes.

7) Fundamentals of Radiative Transfer and greenhouse effect models Electromagnetic spectrum. Solid angle and main radiometric quantities. Black body radiance and its fundamental laws. Kirchhoff's law. The differential equation of the radiative transfer for absorbing and emitting processes. Schwarzschild's solution for a plane parallel atmosphere.

8) The Sun The structure. Luminosity and measure of the Solar Constant. The solar spectrum. Sun radiation and atmospheric particles and gas interaction. Insolation. 

9) Radiative Equilibrium and emission temperature of a Planet Albedo. Basic model for a planet in radiative balance. Emission temperature and variation of the solar constant and of the spherical albedo. Mean surface temperature and emission temperature. 

10) More on radiative transfer Greenhouse 1-d model. Greenhouse parameter. The Venus case and the Sandstrom theorem. Radiative equilibrium in a plane parallel and grey atmosphere. Runaway green-house effect (Venus, Earth and Mars). Time radiative constants. Global energy budgets for multiple planets. 

11) Simple Climatic Models Thermal inertia of an ocean and an atmosphere. 0-d models and feedback processes. Energy balance 1-d climatic models: Budyko-Sellers. Milankovitch theory: orbital parameters and climatic patterns. Experimental data and glacial eras.

Readings/Bibliography

T. Maestri. Planetary Atmospheres. Available directly from the teacher.

C. Bartolini, M. Benelli, L. Solmi: DVD-ROM "Viaggio nel Sistema Solare" (2011) available at the Physics andAstronomy Department viale Berti-Pichat.

John M. Wallace and Peter V. Hobbs. Atmospheric Science: An Introductory Survey Academic Press, 1997.

Joseph W. Chamberlain and Donald M. Hunten. Theory of Planetary Atmospheres: An Introduction to Their Physics and Chemistry Aca- demic Press, 1987.

D. L. Hartmann. Global Physical Climatology Academic Press, 1994.

Murry L. Salby Fundamentals of Atmospheric Physics Academic Press, 1996.

Bradley W. Carroll, Dale A. Ostlie. An introduction to modern astrophysics, Pearson Addison-Wesley, 2007

Teaching methods

The teacher will discuss the program content (6 ects) by using the blackboard and by exploiting the video projector. Simple exercises will be solved during the classes to facilitate the understanding of the theoretical part of the program. It is foreseen the discussion of some of the most recent scientific articles concerning the topics of the course.

Assessment methods

The verification of the student's learning occurs through an oral test that will evaluate the achievements of the main objectives of the course:

*) understanding the physical laws regulating a planet and its evolution *) interpreting simplified physical model applied to a complex system *) ability to identify the main parameters affecting and determining the thermal structure of an atmosphere


The oral test will cover the whole program and allows the student to discuss a brief written research of his choice concerning a specific topic. The oral test will last at about 1 hour and 15 minutes.

Teaching tools

The following items will be available to the Students:
* Lectures notes (on paper and/or electronics).
* Scientific articles useful for the investigation of specific research lines.
* Software algorithms for the numerical solution of specific problems.
* Materials on dvd
* Bibliography and references

Links to further information

https://solarsystem.nasa.gov

Office hours

See the website of Tiziano Maestri