Physics principles in radiometric infrared imaging of clouds in the atmosphere

Abstract

Imaging the atmosphere with a thermal infrared camera can yield a rich variety of information, ranging from the water-vapour content to the spatial distribution of clouds. Such remote sensing measurements are being used to study climate and to characterize ground-station sites for Earth–space optical communications. The key to turning interesting but qualitative images into the highly accurate quantitative images required for this type of research is careful radiometric calibration. This is especially true when using uncooled microbolometer cameras, which are becoming widely available at relatively low cost. When such cameras are calibrated properly, their images illustrate a variety of important basic principles of optics and atmospheric physics related to thermal emission and absorption by atmospheric gases and clouds.