These waves take over an hour to reach the mesopause
emission level and must traverse the stratosphere and mesosphere, which process the wave energy (absorption, breaking, and other effects) via wind shear and critical layers (e.
The final, and possibly the most significant factor in producing ice is the temperature at the mesopause
Theoretical predictions of cooling in the mesopause
indicate that it should be dramatically faster than the warming at ground level,' Burns says.
Moreover, the theories require that the mesopause
be cold enough for condensation to occur.
By 2007, the capability for measuring mesopause
temperatures between 88 and 100 km was added, using a sodium Doppler lidar (Clemesha et al.
It is believed that summer buoyancy waves rising forcibly in the atmosphere have the effect of cooling the mesopause
as the air expands and cools.
Gardner, 1991: Na temperature lidar measurements of gravity wave perturbations of wind, density and temperature in the mesopause
Strictly speaking, NLC is not an 'astronomical' phenomenon, being in the mesopause
at about 83km, but it is part of the solar-terrestrial environment and many aspects of it, including a possible connection with the aurora, are not fully understood.