Climate has a central influence on many human needs and activities, such as agriculture, housing, human health, water resources, and energy use. The influence of climate on vegetation and soil type is so strong that the earliest climate classification schemes where often based more on these factors than on the meteorological variables. While technology can be used to mitigate the effects of unfavorable climatic conditions, climate fluctuations that result in significant departures from normal cause serious problems for modern industrialized societies as much as for primitive ones. The goals of climatology are to provide a comprehensive description of the Earth's climate, to understand its features in terms of fundamental physical principles, and to develop models of the Earth's climate that will allow the prediction of future changes that may result from natural and human causes.