Individual sand grains move in three ways: saltation, creeping,
and suspension. Sand grains bounce or "saltate" slightly
above the surface when blown by the wind. With each bounce, the
grains usually reach heights of less than 5 cm above the surface,
and move horizontally 5-10 cm. The average distance a grain bounces
is the width between the crests of two ripples in the sand. Saltation
accounts for about 95% of a sand grain's movement. A sand grain
"creeps" when it collides with other grains, causing it
to roll or make small jumps. Creep may account for about 4% of a
grain's movement. Finally, a sand grain moves by "suspension"
when it is blown high into the air. Suspension accounts for 1% or
less of an individual sand grain's movement.
