Mechanics of Sand Transport - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 36

Fig. 4.1 Cartoon of different
types of particle transportation by
the wind. Image courtesy of Nick
Lancaster

Fig. 4.2 A dramatic photo of an
approaching haboob (dust storm
front), taken by a soldier in Iraq.
Here dust is in suspension.
Wikimedia Commons

Although not the subject of this topic, airborne dust and
sand transport are often considered together (conferences and
conference sessions on aeolian processes cover them both).
Airborne dust is an important factor in air quality and the
nutrient balance, Saharan dust is an important factor in pro-
viding iron to the oceans and even to the Amazon basin. Dust
is a significant factor in controlling climate (on both Earth and
Mars) and in the use of solar power on both worlds. Mars is, of
course, famous for both dust devils and for dust storms, which
also happen occasionally on Earth (Fig. 4.2 ).

4.2 Fluid Forces on Particles

The interaction of objects with moving fluids is funda-
mental in a number of fields, from gravel moving in a river
to a fighter jet moving in air. Each one has developed a set
of conventions in formulation and nomenclature, even
though the underlying process is the same. Thus some
works in aeolian studies refer to a 'threshold parameter', a
'Shields parameter' is used in hydraulic sedimentology,
while aerospace engineers have a 'drag coefficient'. All of