Star dunes such as this one from Namibia and the lower one from Great
Sand Dunes National Monument form in areas with bi-modal wind directions.
Top Image courtesy of NASA .Bottom image from Great Sand Dunes National Monument.
Wind Regime: As the wind direction
rose diagram indicates, these dunes occur in bi-modal wind environments with a large amount of directional variability.
Sand rose illustrates the annual wind regime for Star dunes in Libya.
Wind Rose from Fryberger and Dean (1979)
Try it in the Simulator
For Star Dunes Try These Simulator Settings:
Sand Cover: 10%
Prevailing Wind Direction:
Wind Direction Variability:
75% - Note that for Star Dunes, the Simulator will regularly shift wind directions by 180o