Atmospheric science is the study of the earth's atmosphere, from near the ground where much of the "weather" occurs, to the upper reaches of the stratosphere and beyond, where there are winds and pressure patterns but few clouds and convective motions. From a global perspective, the atmosphere consists of a rotating, thin layer of gas which can be studied by the methods of geophysical fluid dynamics. For the large scales, winds, temperature fronts and planetary waves play a central role in research. At smaller scales the atmosphere's detailed physics and chemistry are of considerable interest: the role of cloud droplets in making rain, and how the incoming solar radiation heats the earth and oceans which in turn warm the air above by outgoing radiation and convection. Another topic of importance is the study of weather and weather forecasting, which necessarily draws on both the dynamical and physical processes described above. Finally, in today's world of ever increasing environmental concern, questions of climate change are of considerable interest to many atmospheric scientists.