The Earth, including its gaseous envelope, is a very small interactive part of the solar system. As such, it is also a part of the interactive dynamic structure of the galaxy and the universe. Existing within this dynamic material and energetic macrocosm, the Earth is subject to varying forces and energy fields. Though the Earth, in turn, affects the macrocosm, its effect is small indeed. Answers to questions concerning climate and its changes are difficult to formulate. Why? Because many authors have tried to define the "climate" and have a different understanding of what climate is. Until one can define climate adequately and its characteristics can be stated, and the definition is accepted, prediction of changes or any future state will be relatively untenable. There probably are as many definitions of climates as there are of readers interested in climate. Individual states or the state at any specified instant of time may be termed weather. Physical and chemical measurements of various weather elements may be made. These characterize or describe the instantaneous states of weather. It is collectives of these data, such as temperatures, precipitation, lack of precipitation, etc., that may be used to make some definitive statements about the climate in which these were measured. The user must not forget that it is the total ensemble of all subcollectives that constitute a measure of the climate. The collective state includes the potential to determine departures from norms (normals), the relationships among the information packets, and the inherent variabilities that these contain. If some weather element has not been measured or is as yet undefined, then the climate collective is deficient. The user may not be aware of such a deficiency. Even the field of climatology-the study of climate-has its proponents for different phases of the climate. Their arguments, though seemingly precise in themselves, may be biased and may not provide an accurate picture or perspective of climate. This publication was originally intended as a contribution to a 15-volume series in "World Survey of Climatology" as a part of V. l. A previous contribution was a small chapter in V. 4 in 1969. Work on this was begun in 1977. The subject was climatic elements. Trace gases have become increasingly important in the study of climatology. Here, climatic elements include trace gases as well as measures of the expected physical elements-wind, temperature, precipitation, radiation, and others. There are many references. The requisite permissions were obtained. The expected publishers indicate that they do not wish to publish this material. Therefore, this procedure is chosen to place the material in your hands. You will find the material to be informative and useful. Since the principal author assembled the technical contents given within this publication over a number of years, some of the technical content may not be representative of the latest state-of-the art information.
