The study of climate and weather conditions averaged over a period of time is within the domain of climatology. It studies a number of analog techniques for weather forecasting and various climate models for the future projections of weather and climate systems. Climatology studies are approached from different dimensions like paleoclimatology, paleotempestology and historical climatology. Paleoclimatology strives to understand past climates by studying records of ice cores and tree rings. Paleotempestology determines the frequency of hurricanes over millennia using similar records. Climate indices are used for the characterization of the different climatic mechanisms that contribute to daily weather. They are based on the twin objectives of simplicity and completeness. Some of such indices are El Niño–Southern Oscillation, North Atlantic oscillation, Madden-Julian oscillation, etc. This book covers in detail some existing theories and innovative concepts revolving around climatology. Different approaches, evaluations, methodologies and advanced studies on climatology have been included herein. Climatologists, meteorologists, researchers and students associated with this field will benefit alike from this book.