Middle atmosphere dynamics and composition

Aspects of the dynamics and composition of that region of the earth atmosphere lying above the tropopause but below 100 km are considered as they relate to processes at middle and high latitudes. The physics of the summer to winter reversal of the direction of the middle atmosphere jet is discussed, along with the effects of planetary waves on the mean zonal flow, which occasionally produce sudden stratosphere warming events. The chemistry of the two middle atmospheric trace constituents ozone and nitric oxide, which play dominant roles in atmospheric radiation balance and lower ionospheric structure, respectively, is then examined, and the importance of transport in determining their distribution is pointed out.