The study of long-term weather patterns and climate on the earth and other planets. The Climatologist is an expert on the physical processes that determine the climate of the atmosphere. He is highly knowledgeable about global changes that can effect the climate, such as ocean currents, changes in the planetary orbit, variations in solar output, increases in greenhouse gases, and volcanic eruptions. He studies records of past climates, including temperature and precipitation changes, to make predictions about near-term weather patterns. He can also estimate the effect of human activities on climates. Paleoclimatology is the study of the climate in the distant past, such as glacial eras.