The climate of the Earth has undergone many changes and for those times when geologic data are widespread and abundant the Mesozoic appears to have been one of the warmest intervals. This was a time during which the single continent Pangea disintegrated into continental units similar to those of today, a time when there were no significant polar ice caps and sea level was generally much higher than at the present time, and a time when dinosaurs apparently dominated terrestrial faunas and the flowering plants evolved. Understanding this alien world, ancestral to ours, is intrinsically interesting, intellectually challenging, and offers opportunities for more effective targeting of sites where commercially important geological resources may be found. It also provides critical insights into the operation of coupled Earth systems (biospheric, atmospheric, hydrospheric and geospheric) under extreme 'greenhouse' conditions, and therefore may have relevance to possible future global change. Our intention in organizing this Discussion Meeting was to bring together those who gather and interpret geologic data with those who model global climates from first principles. The community of workers who study the Quaternary have made significant advances by integrating and comparing palaeodata and climate model experiments. Although we have focused not on the Quaternary 'icehouse' but on the Mesozoic 'hothouse' climate we are well aware that approaches used in the study of the Quaternary may have relevance to earlier times.

The climate of the Earth has undergone many changes and for those times when geologic data are widespread and abundant the Mesozoic appears to have been one of the warmest intervals. This was a time during which the single continent Pangea disintegrated into continental units similar to those of today, a time when there were no significant polar ice caps and sea level was generally much higher than at the present time, and a time when dinosaurs apparently dominated terrestrial faunas and the flowering plants evolved. Understanding this alien world, ancestral to ours, is intrinsically interesting, intellectually challenging, and offers opportunities for more effective targeting of sites where commercially important geological resources may be found. It also provides critical insights into the operation of coupled Earth systems (biospheric, atmospheric, hydrospheric and geospheric) under extreme 'greenhouse' conditions, and therefore may have relevance to possible future global change. Our intention in organizing this Discussion Meeting was to bring together those who gather and interpret geologic data with those who model global climates from first principles. The community of workers who study the Quaternary have made significant advances by integrating and comparing palaeodata and climate model experiments. Although we have focused not on the Quaternary 'icehouse' but on the Mesozoic 'hothouse' climate we are well aware that approaches used in the study of the Quaternary may have relevance to earlier times.

This book gives a coherent development of the current understanding of the fluid dynamics of the middle latitude atmosphere. It is primarily aimed at post-graduate and advanced undergraduate level students and does not assume any previous knowledge of fluid mechanics, meteorology or atmospheric science. The book will be an invaluable resource for any quantitative atmospheric scientist who wishes to increase their understanding of the subject. The importance of the rotation of the Earth and the stable stratification of its atmosphere, with their implications for the balance of larger-scale flows, is highlighted throughout. Clearly structured throughout, the first of three themes deals with the development of the basic equations for an atmosphere on a rotating, spherical planet and discusses scale analyses of these equations. The second theme explores the importance of rotation and introduces vorticity and potential vorticity, as well as turbulence. In the third theme, the concepts developed in the first two themes are used to give an understanding of balanced motion in real atmospheric phenomena. It starts with quasi-geostrophic theory and moves on to linear and nonlinear theories for mid-latitude weather systems and their fronts. The potential vorticity perspective on weather systems is highlighted with a discussion of the Rossby wave propagation and potential vorticity mixing covered in the final chapter.