Python Notes - University of Chicago

Contents

Preface

i

Contents

2

1 Getting Started

3

1.1

1.2

1.3

1.4

Basic Skills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

1.1.1

Using xterms and logging in to the server . . . . . . . . . . . .

4

1.1.2

About the Python Shell and idle . . . . . . . . . . . . . . . .

5

1.1.3

Running Python Locally . . . . . . . . . . . . . . . . . . . . .

7

Fun with Python . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8

1.2.1

Basic operations

. . . . . . . . . . . . . . . . . . . . . . . . .

8

1.2.2

Lists, tuples and strings . . . . . . . . . . . . . . . . . . . . .

9

1.2.3

Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.2.4

Getting help . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.2.5

Program control: Looping, conditionals and functions . . . . . 12

Progressing in Python . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.3.1

Writing your own modules and executable scripts . . . . . . . 17

1.3.2

List comprehension . . . . . . . . . . . . . . . . . . . . . . . . 18

1.3.3

Using objects in Python . . . . . . . . . . . . . . . . . . . . . 18

1.3.4

The Numeric array package . . . . . . . . . . . . . . . . . . . 20

1.3.5

The Curve object and its uses . . . . . . . . . . . . . . . . . . 25

Advanced Python Topics . . . . . . . . . . . . . . . . . . . . . . . . . 28

1.4.1

Defining your own objects . . . . . . . . . . . . . . . . . . . . 28

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1.4.2

Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

1.4.3

Writing text data to files . . . . . . . . . . . . . . . . . . . . . 37

1.4.4

Reading text data from a file . . . . . . . . . . . . . . . . . . 38

2 Thermodynamics and vertical structure

39

2.1

Tutorial: Getting physical properties and constants . . . . . . . . . . 40

2.2

Problem set: Dry thermodynamics . . . . . . . . . . . . . . . . . . . 41

2.3

2.2.1

Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

2.2.2

Ideal gas law . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

2.2.3

Atmospheric composition and mixing ratios . . . . . . . . . . 42

2.2.4

Specific heat: Some basic problems . . . . . . . . . . . . . . . 42

2.2.5

Temperature-dependent specific heat . . . . . . . . . . . . . . 43

2.2.6

Potential Temperature and the Dry Adiabat . . . . . . . . . . 43

2.2.7

Inhomogeneous mixtures; Potential density and ��virtual temperature�� . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Data Lab: Analysis of temperature profile data . . . . . . . . . . . . 44

2.3.1

Analysis of tropical Earth soundings . . . . . . . . . . . . . . 44

2.3.2

Analysis of midlatitude Earth soundings . . . . . . . . . . . . 46

2.3.3

Analysis of planetary soundings . . . . . . . . . . . . . . . . . 47

2.4

Tutorial: Numerical solution of differential equations . . . . . . . . . 48

2.5

Problem set: Hydrostatics . . . . . . . . . . . . . . . . . . . . . . . . 52

2.6

2.5.1

Mass of carbon in the Earth��s atmosphere . . . . . . . . . . . 52

2.5.2

Mass of Titan��s atmosphere . . . . . . . . . . . . . . . . . . . 52

2.5.3

The dry adiabatic lapse rate . . . . . . . . . . . . . . . . . . . 53

2.5.4

Heat capacity of atmospheric columns . . . . . . . . . . . . . 53

Problem set: Moist thermodynamics . . . . . . . . . . . . . . . . . . 53

2.6.1

Latent heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

2.6.2

Using the simplified form of the Clausius-Clapeyron relation . 53

2.6.3

Methane on Titan . . . . . . . . . . . . . . . . . . . . . . . . . 54

2.6.4

Boiling vs. evaporation . . . . . . . . . . . . . . . . . . . . . . 54

vi

1

2.6.5

Comparison of idealized vs. empirical saturation vapor pressure 55

2.6.6

Variable latent heat . . . . . . . . . . . . . . . . . . . . . . . . 55

2.6.7

Latent heat from Clausius-Clapeyron . . . . . . . . . . . . . . 55

2.6.8

Water content of the atmosphere . . . . . . . . . . . . . . . . 57

2.6.9

CO2 condensation in the Martian Winter . . . . . . . . . . . . 57

2.6.10 CO2 condensation on Snowball Earth . . . . . . . . . . . . . . 57

2.6.11 Moist adiabat for atmosphere with two condensible components 58

2.6.12 Springtime for Europa . . . . . . . . . . . . . . . . . . . . . . 58

2.7

Computation Lab: Computing the moist adiabat . . . . . . . . . . . 59

2.8

Problem set: Rayleigh fractionation . . . . . . . . . . . . . . . . . . . 60

3 Elementary radiation balance problems

61

4 Continuous atmosphere radiation problems

63

5 Radiative-convective model problems

65

6 Scattering problems

67

7 Data analysis problems: Earth radiation budget

69

8 Surface energy budget problems

71

9 Seasonal Cycle problems

73

10 Atmospheric evolution modelling problems

75

11 Meridional heat transport modelling problems

77

12 Appendix A: Hints for the user of Unix and its relatives

79

12.1 Simple Unix for the masses . . . . . . . . . . . . . . . . . . . . . . . . 79

12.2 A few useful Unix utilities . . . . . . . . . . . . . . . . . . . . . . . . 80

12.3 Nasty Unix stuff I hope you won��t have to deal with . . . . . . . . . . 80

12.4 Public domain software to install on the server . . . . . . . . . . . . . 83

2

12.5 Installing the courseware . . . . . . . . . . . . . . . . . . . . . . . . . 85

Chapter 1

Getting Started

3

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