I caught this dust devil while we were coming back from Joshua Tree National Park yesterday. We were on the western end of I-10 driving about 80 mph (speed limit is 75 mph). I guess all my years of taking pictures from a moving car have paid off! Not to mention a little help from Aperture to correct for the tinted window… and Topaz Clarity.
A dust devil, like a tornado, is a weather phenomenon. Dust devils form as a swirling updraft under sunny conditions during fair weather, rarely coming close to the intensity of a tornado. According to Wikipedia, certain conditions increase the likelihood of dust devil formation:
- Flat barren terrain, desert or tarmac: Flat conditions increase the likelihood of the hot-air “fuel” being a near constant. Dusty or sandy conditions will cause particles to become caught up in the vortex, making the dust devil easily visible.
- Clear skies or lightly cloudy conditions: The surface needs to absorb significant amounts of solar energy to heat the air near the surface and create ideal dust devil conditions.
- Light or no wind and cool atmospheric temperature: The underlying factor for sustainability of a dust devil is the extreme difference in temperature between the near-surface air and the atmosphere. Windy conditions will destabilize the spinning effect.