|What is a Dust
Mojave Desert-Between Barstow &
|Dust devils are a
common wind phenomenon that occurs over the deserts of
southern California. |
These dust-filled cyclones
form by strong heating of the surface, and normally are
much smaller and intense than a tornado.
diameter of a dust devil ranges from 10 to 300 feet,
with an average height of approximately 500 to 1,000
feet...normally only last a few minutes.
Dust devils form in areas of strong
surface heating and usually occur under sunny skies and light
winds, when the ground can warm the air to temperatures well
above the temperatures just above the ground.
Once the ground heats up enough, a
localized pocket of air will quickly rise through the cooler
above it. The sudden uprush of hot air causes air to speed
horizontally inward to the bottom of the newly-forming vortex.
This rapidly rising pocket of air may begin to rotate, and if
it continues to be stretched in the vertical direction, will
increase in rotation speed. This increase in rotation speed
from vertical stretching is similar to the increased spinning
of an ice skater as they bring their arms in toward their
bodies. As more hot air rushes in toward the developing vortex
to replace the air that is rising, this spinning effect is
intensified. As the air rises, it cools and eventually will
descend back through the center of the vortex. Under optimal
conditions, a balance between the hot air rising along the
outer wall of the vortex and the cooler air sinking in the
vortex occurs. The dust devil then begins to move across the
ground, picking up more and more dust, which highlights the
vortex making it visible to the eye. The dust devil, once
formed, is a funnel-like chimney through which hot air moves
both upward and circularly. If a steady supply of warm
unstable air is available for the dust devil, it will continue
to move across the ground. However, once the warm unstable air
is depleted or the balance is broken in some other way, the
dust devil will break down and dissipate.
|...Here in southern
Dust devels are often visibible
while driving along the 10 FWY from Palm Springs east to
the Colorado River,
along the 15 FWY from Hesperia
northeast to the Nevada state line,
along the 14
Freeway through the Antelope Valley and...
58 from Mojave east to Barstow.
Along the 15 Freeway near
Some of the
information above, courtesy of the...
Service website in Flagstaff, Arizona.