Preface ........................................................ ix
Part I. Anatomy of a cyclone .................................. 1
1. Anatomy of a cyclone ........................................ 3
1.1. A 'typical' extra-tropical cyclone .................... 3
1.2. Describing the atmosphere ............................. 4
1.3. Air masses and fronts ................................. 9
1.4. The structure of a typical extra-tropical cyclone .... 14
Review questions ..................................... 20
2. Mathematical methods in fluid dynamics ..................... 23
2.1. Scalars and vectors .................................. 23
2.2. The algebra of vectors ............................... 23
2.3. Scalar and vector fields ............................. 27
2.4. Coordinate systems on the Earth ...................... 27
2.5. Gradients of vectors ................................. 28
2.6. Line and surface integrals ........................... 31
2.7. Eulerian and Lagrangian frames of reference .......... 34
2.8. Advection ............................................ 35
Review questions ..................................... 38
3. Properties of fluids ....................................... 41
3.1. Solids, liquids, and gases ........................... 41
3.2. Thermodynamic properties of air ...................... 42
3.3. Composition of the atmosphere ........................ 43
3.4. Static stability ..................................... 46
3.5. The continuum hypothesis ............................. 50
3.6. Practical assumptions ................................ 50
3.7. Continuity equation .................................. 51
Review questions ..................................... 53
4. Fundamental forces ......................................... 57
4.1. Newton's second law: F = ma .......................... 57
4.2. Body, surface, and line forces ....................... 57
4.3. Forces in an inertial reference frame ................ 58
4.4. Forces in a rotating reference frame ................. 66
4.5. The Navier-Stokes equations .......................... 72
Review questions ..................................... 74
5. Scale analysis ............................................. 79
5.1. Dimensional homogeneity .............................. 79
5.2. Scales ............................................... 80
5.3. Non-dimensional parameters ........................... 80
5.4. Scale analysis ....................................... 84
5.5. The geostrophic approximation ........................ 87
Review questions ..................................... 91
6. Simple steady motion ....................................... 93
6.1. Natural coordinate system ............................ 93
6.2. Balanced flow ........................................ 95
6.3. The Boussinesq approximation ........................ 104
6.4. The thermal wind .................................... 105
6.5. Departures from balance ............................. 108
Review questions .................................... 114
7. Circulation and vorticity ................................. 119
7.1. Circulation ......................................... 119
7.2. Vorticity ........................................... 124
7.3. Conservation of potential vorticity ................. 126
7.4. An introduction to the vorticity equation ........... 130
Review questions .................................... 132
8. Simple wave motions ....................................... 135
8.1. Properties of waves ................................. 135
8.2. Perturbation analysis ............................... 138
8.3. Planetary waves ..................................... 140
Review questions .................................... 147
9. Extra-tropical weather systems ............................ 149
9.1. Fronts .............................................. 149
9.2. Frontal cyclones .................................... 152
9.3. Baroclinic instability .............................. 161
Review questions .................................... 162
Part II. Atmospheric phenomena ............................... 165
10. Boundary layers ........................................... 167
10.1. Turbulence .......................................... 168
10.2. Reynolds decomposition .............................. 169
10.3. Generation of turbulence ............................ 172
10.4. Closure assumptions ................................. 173
Review questions .................................... 181
11. Clouds and severe weather ................................. 183
11.1. Moist processes in the atmosphere ................... 183
11.2. Air mass thunderstorms .............................. 191
11.3. Multi-cell thunderstorms ............................ 193
11.4. Supercell thunderstorms and tornadoes ............... 194
11.5. Mesoscale convective systems ........................ 196
Review questions .................................... 197
12. Tropical weather .......................................... 199
12.1. Scales of motion .................................... 199
12.2. Atmospheric oscillations ............................ 203
12.3. Tropical cyclones ................................... 205
Review questions .................................... 208
13. Mountain weather .......................................... 209
13.1. Internal gravity waves .............................. 209
13.2. Flow over mountains ................................. 217
13.3. Downslope windstorms ................................ 226
Review questions .................................... 230
14. Polar weather ............................................. 233
14.1. Katabatic winds ..................................... 233
14.2. Barrier winds ....................................... 242
14.3. Polar lows .......................................... 247
Review questions .................................... 249
15. Epilogue: the general circulation ......................... 251
15.1. Fueled by the Sun ................................... 251
15.2. Radiative-convective equilibrium .................... 253
15.3. The zonal mean circulation .......................... 254
15.4. The angular momentum budget ......................... 259
15.5. The energy cycle .................................... 261
Appendix A - symbols .......................................... 265
Appendix В - constants and units .............................. 271
Bibliography .................................................. 273
Index ......................................................... 277
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