Thirty-four miles away by car in Alamosa, prevailing winds
are from the southwest throughout the yearas illustrated by arrowhead
in the wind rose diagram. This wind pattern continues to the southwest
corner of the dunefield.
Over the years, sand and small dunes migrate in this southwestern,
unimodal wind pattern toward the main dunefield. Close to the dunefield,
however, wind patterns change. It is not uncommon for winds to emerge
from any of the three mountain passesMusic, Medano and Moscaany
time of the year. The dunefield's bimodal and complex wind regime contribute
to two distinctive dune types: reversing
and star dunes.
If you scrutinize the relief map above, take notice of the
Sand Creek Star Dune complex in the northwest corner of the dunefield.
Star dunes are oriented in many directions, which indicate the occurrence
of a complex wind regime. And notice that a bimodal wind regime is apparent
in the southern region of the dunefield by the existence of the north-south
trending Medano Creek dune ridges.