Provides a unique and unifed approach to the methodology of optical atmospheric observations from the troposphere through the thermosphere, which allows the practitioner to choose the best instrument for a given measurement.Describes state-of-the-art atmospheric observing instruments with an eye to future developments.Includes problems designed to test and enhance students' unerstanding of the material presented in each chapter.Contains concise descriptions of selected current and planned spectral imagers, including the Fabry-Perot spectrometer, the Michelson interferometer and the diffraction grating spectrometer.Written from a scientific perspective in an engineering framework, this work is accessible to atmospheric scientists and instrumentation engineers alike.