The saltation of sand involves

a. spherical grains rolling along the surface of dunes

b. grains traveling short distances (approximately 1 m) in the air

c. grains traveling long distances (approximately 1-100 km) in the air by strong winds

d. the mixing of mineral sand and salt to form a weakly cemented soil

b. grains traveling short distances (approximately 1 m) in the air

Explanation:

Wind is a very efficient erosion agent, and its action, particularly in areas of arid, semi-arid and desert climates, is responsible for transporting and depositing large volumes of sediments with the development of a typical wind landscape.

The diameter of the sand grains transported by the wind averages between 0.15 and 0.30 mm, with some fine grains up to 0.006 mm, all particles smaller than 0.006 mm are classified as dust. A grain the size of the dust is carried high in the air and a grain the size of the sand is carried forward near the ground by jumping (see figure 1). As the particle size increases, the attraction of gravity and air resistance also increase.

The soil surface particles are transported by the wind in three ways:

- By drag: the thickest particles (500 - 2000 microns).

- By saltation: medium particles (100-500 microns).

- In suspension: the smallest and lightest particles (<100 microns, 0.2 mm).

The saltation moves the particles by small jumps, in the direction of origin of the wind and normally does not remove them more than 1 centimeter above the ground. An individual grain rolls forward driven by the wind, until it bounces with a second grain. Once in the air, it is carried forward by the wind and drawn to the ground by gravity. It follows a parabolic path falling on the ground with an angle between 10º and 16º, and usually traveling short distances.