It is now clear that atmospheric aerosols contribute substantially to global climate change and the importance of these processes must now be assessed. This book provides a comprehensive overview of present-day knowledge concerning atmospheric aerosols, how to characterise accurately the principal types present, their properties and their climatic impact. It also discusses the interaction of stratospheric aerosols produced in volcanic eruptions and the problem of estimating the climatic impact of such eruptions. Of especial interest is a discussion of the ongoing debate concerning the effects of clouds on atmospheric absorption of solar radiation, and the influence of this process on climate change. Whilst concluding that at present it is still not possible to simulate global change reliably, this book provides a stepping stone to understanding the complex processes involved and the uncertainties arising from the effects of aerosols and clouds upon climate.