The study of the Earth's atmosphere along with the processes related to it is known as atmospheric science. It is also involved in studying the effects which other systems have on it. Some of the sub-disciplines which fall under atmospheric science are meteorology, climatology and aeronomy. Meteorology deals primarily with weather forecasting using atmospheric physics and atmospheric chemistry. Climatology studies the long and short term changes in the atmosphere which define average climate of a particular geographical location. Aeronomy is concerned with the study of the higher layers of the atmosphere, focusing particularly on the processes of dissociation and ionization. This textbook provides comprehensive insights into the field of atmospheric science. It presents this complex subject in the most comprehensible and easy to understand language. The book will serve as a valuable source of reference for graduate and post graduate students.