Cover

Half-title

Title

Copyright

Dedication

Contents

Preface

1 Wind as a geological process

1.1 Introduction

1.2 Approach to the problem

1.3 Significance of aeolian processes

1.3.1 Relevance to Earth

1.3.2 Relevance to planetary science

1.4 Aeolian features on the planets

1.4.1 Earth

1.4.2 Mars

1.4.3 Venus

1.4.4 Titan

2 The aeolian environment

2.1 Introduction

2.2 Properties of atmospheres

2.2.1 Hydrostatic equilibrium

2.2.2 Adiabatic lapse rate

2.3 Comparisons of planets and their atmospheres

2.3.1 Origin of atmospheres

2.4 The atmospheric boundary layer

2.4.1 Turbulence

2.4.2 Turbulent boundary layer

2.4.3 Effect of non-neutral stability

2.4.4 Pressure gradient and Coriolis forces

2.4.5 Friction forces - the Ekman spiral

2.4.6 Diffusion

2.5 Windblown particles

2.6 Processes of particle formation

2.6.1 Weathering

2.6.2 Cataclastic processes

2.6.3 Volcanism

2.6.4 Precipitation and biological activity

2.6.5 Aggregation

2.7 Sand and dust sources

3 Physics of particle motion

3.1 Introduction

3.2 Classification of motion

3.3 Threshold of motion

3.3.1 Particle forces

3.3.2 Theoretical expressions for threshold

3.3.3 Wind tunnel experiments

3.3.4 Roughness effects

3.3.5 Effects of moisture and other cohesive forces

3.3.6 Vortex threshold

3.3.7 Threshold predictions for other planets

3.4 Particle trajectories

3.4.1 Particle forces

3.4.2 Saltation trajectories

3.4.3 Predictions of saltation trajectories

3.5 The saltation layer

3.5.1 Particle flux

3.5.2 Concentration distribution

3.5.3 Mass transport predictions for Mars and Venus

3.5.4 Effect of saltation on wind speeds near the surface

4 Aeolian abrasion and erosion

4.1 Introduction

4.2 Aeolian abrasion of rocks and minerals

4.2.1 Mechanics of abrasion

4.2.2 Susceptibility to abrasion

4.3 Ventifacts

4.3.1 Ventifact morphology

4.3.2 Factors involved in ventifact formation

4.3.3 Ventifacts on Mars and Venus

4.4 Rates of aeolian abrasion: Earth and Mars

4.5 Yardangs

4.5.1 General characteristics

4.5.2 Yardang localities

4.5.3 Yardang formation

4.5.4 Yardangs on Mars

5 Aeolian sand deposits and bedforms

5.1 Introduction

5.1.1 Sand waves

5.2 Ripples

5.2.1 Ripple morphology

5.2.2 Internal structures in ripples

5.2.3 Ripple formation

5.2.4 'Fluid drag' ripples, 'normal' ripples, and 'mega-ripples'

5.2.5 Ripples on other planets

5.3 Sand dunes

5.3.1 Dune classification and formation

5.3.2 Transverse dunes

5.3.3 Longitudinal dunes

5.3.4 Parabolic dunes

5.3.5 Dome dunes

5.3.6 Star dunes

5.3.7 Other dunes

5.3.8 Internal structures in dunes

5.3.9 Dune migration and control

5.3.10 Clay dunes

5.3.11 Dunes on Mars

5.4 Sand shadows and drifts

5.4.1 'Drifts' on Mars and Venus (?)

5.5 Sand sheets and streaks

6 Interaction of wind and topography

6.1 Introduction

6.2 Atmospheric motions

6.2.1 General circulation and rotational flows

6.2.2 The vortex

6.3 Topographical effects on surface winds

6.3.1 The effects of mountains

6.3.2 Separated flows

6.4 Wind streaks

6.4.1 Modes of formation

6.4.2 Streaks on Earth

6.4.3 Wind tunnel streak simulation

6.4.4 Amboy field experiment

6.4.5 Wind streaks on Mars

6.4.6 Wind streaks on Venus and Titan

7 Windblown dust

7.1 Introduction

7.2 Dust storms on Earth

7.2.1 Dust storm development and effect on climate

7.2.2 Characteristics of aeolian dust

7.2.3 Erosion of agricultural land

7.2.4 Dust devils

7.2.5 Fugitive dust

7.3 Dust storms on Mars

7.3.1 Martian great dust storms

7.3.2 Martian great dust storms clearing

7.3.3 Local dust storms

7.4 Dust deposits

7.4.1 Loess on Earth

7.4.2 Dust deposits on Mars

Appendix A: Nomenclature and symbols

Nomenclature and symbols

Appendix B: Small-scale modeling of aeolian phenomena in the wind tunnel

Small-scale modeling of aeolian phenomena in wind tunnels

Transport rate similitude

Particle trajectory similitude

Effect of Froude number and density ratio

The similitude function

Glossary

References

Index