Whistler Waves
A right-hand circularly polarized electromagnetic wave mode propagating along magnetic field lines in a magnetized plasma below electron cyclotron frequency.
Governing formula
v_phase = c √(ω ω_ce) / ω_pe (For ω ≪ ω_ce)
SI unit
Audio Frequency Pitch Glissando (kHz)
In depth
Higher frequency wave components travel faster than lower frequency components along geomagnetic field lines. Audio receivers convert passing whistler radio signals into characteristic descending pitch tones ('whistles').
Examples in the real world
Lightning discharges generating magnetospheric whistler wave modes detected by planetary space probes.