We are now approaching the point where we can start investigating Solar-Terrestrial relations from a systems point of view. The terrestrial
system remains in a quasi-stationary state with respect to the solar energy inputs with the lower neutral atmosphere being especially stable. Of
interest, in the study of the terrestrial response, is identifying which Solar influences are of most importance and how the terrestrial system
(troposphere, stratosphere, mesosphere, thermosphere and ionosphere) accommodates the associated variability. Most of the solar variability is
associated with the Solar wind and radiation in the ultra-violet and x-ray spectral regions. The magnitude of the resulting terrestrial response is
roughly inversely proportional to the atmospheric density with very little direct response in the stratosphere and troposphere. Nevertheless, there
is an indirect lower atmosphere response which is larger than expected. In addition, in recent years it has become clear that the lower atmosphere
has considerable influence on the upper atmosphere through wave coupling. This session is directed toward identifying, the solar inputs of most
importance to the terrestrial system, understanding how these inputs are accommodated, understanding wave coupling processes and investigating the
causes of the terrestrial lower atmosphere response to solar variability. Contributions involving observational  studies and models (including
whole atmosphere models) which provide insights into which aspects of solar variability are of most importance and the nature of the terrestrial
response are welcomed.