In this audio and accompanying slides, I answer the question, "Describe how dust devils normally form."

1. Formation of Dust Devils
By Sarah Allen

2. Dust Devils

3. Ideal Conditions
• Clear skies- the sun heats the ground causing
a temperature differential between the
ground and the air
• Low wind sheer- allows rotational motion
• Flat terrain- makes it more likely the ground
will be uniformly warmer than the air

4. Formation
• Hot air moves rapidly upward from ground-level
through colder, lower pressure atmospheric air
• The air rotates as it rises
• As the column stretches upward, the speed of
rotation increases and ground friction causes it to
move forward
• As the air moves upward, it cools and eventually
leaves the system
• The system will dissipate when it is no longer fed
by warm surface air

5. Source
Junshi Ito, Hiroshi Niino, and Mikio Nakanishi,
2013: Formation Mechanism of Dust Devil Like
Vortices in Idealized Convective Mixed Layers. J.
Atmos. Sci, 70, 1173-1186
Image:
http://solar.njit.edu/~cdenker/images/dust_devi
l.jpg