FAQ – Deserts
In periods of prolonged drought, vegetation and soil moisture, which typically hold together desert soils, is reduced such that when strong winds occur, they can produce particularly strong dust storms (haboobs).
For a given type of material, particulate materials at smaller sizes are typically brighter than particles at larger sizes. This phenomenon is due to scattering effects (increase in ratio of surface scattering to volume scattering) as light encounters particulate mixtures. Decreased strengths of absorption features at small particle sizes may also contribute. Also, in some environments, dust is derived from a different source than sand and can be a different composition. If the source of the dust is lighter in tone than the source of the sand, the dust will also be lighter than the sand.
You will find references to both inches and centimeters when the average annual amount of precipitation for a desert is discussed. Most deserts have average annual precipitation of less than 16 inches, or 40 centimeters.