Terrestrial dust devils are known to be triboelectric generators: electric charge is generated and exchanged via the mixing and colliding of moving grains. Static electric fields from the structures have been previously reported, this in excess of 1/2 kV/m at a couple hundred meters from the devil. In this work, we report on AC magnetic measurements made during the passage of an intense ~10-m wide, couple hundred-meter tall dust devil in the Nevada desert. The devil-related magnetic activity appears in two forms: Impulsive extremely-low-frequency (ELF: 30-300 Hz) static discharges to the instrument as the sensor became immersed directly into the devil's electrified dust and ultra-low-frequency (ULF: 3-30 Hz), continuous emissions that were sensed remotely as the storm approached and receded from the mobile station. The latter is a new finding not previously reported. Such measurements not only prove that individual dust grains within the devil are charged, but that the grains are transported in bulk to form an extended, coherent radiation source.
Geophysical Research Letters
- Pub Date:
- January 2003
- Meteorology and Atmospheric Dynamics: Atmospheric electricity;
- Atmospheric Composition and Structure: Planetary atmospheres (5405;
- Exploration Geophysics: Magnetic and electrical methods