Dust modification of the plasma conductivity in the Earth's mesosphere

As the Hall and the Ohm diffusion are comparable below 80km, the low frequency (∼10−4−10−5s−1) long wavelength (∼103−104km) waves will be damped at this altitude with the damping rate typically of the order of few minutes. Therefore, the ultra-low frequency magnetohydrodynamic waves can not originate below 80km in the mesosphere. However, above 80km since Hall effect dominates Ohm diffusion the mesosphere can host the ultra-low frequency waves which can propagate across the ionosphere with little or, no damping.