Preface Climate is the long-term aggregate atmospheric condition produced by day-to-day weather. It includes averages, extremes, variabilities and temporal and spatial distributions of numerous meteorological features computed for periods ranging from months to decades or longer. Elements of climate pervade the workings of the natural environment, often influencing and sometimes controlling human activities and commerce. In a wide range of occupations, plans and decisions may be improved by consideration of climatological factors. Wyoming's mid-continent location, high altitude and wide range of irregular topography lead to a climate which is far from uniform and often severe. Therefore, local and regional climatological information may be of even greater importance here than in many other states. As Wyoming's population and industry continue to grow, the demand and uses for climatological information will also increase.
From the architect to the zoologist, people involved in dozens of diverse activities can benefit in ways large and small from proper consideration of climatological information in their plans, decisions and studies. Climate data are frequently consulted, for example, by farmers, ranchers, engineers, hydrologists, architects, construction companies, government planners, wildlife and recreation managers, utilities, mining and energy exploration companies, attorneys, insurance companies, transportation businesses, teachers, homeowners, small business owners, scientists, vacationers and others. The data are gainfully applied to hundreds of different practical problems in ways which reach far beyond any curiosity or trivia value they might possess.
Meteorological measurements are routinely made at hundreds of locations in Wyoming. A dense network of stations measures precipitation and temperature, but observations of most other weather parameters, including humidity and wind, are sparse in the state. Summaries and tabulations of various aspects of Wyoming's climate have been published in scattered bulletins and reports by various organizations. Each source of data is useful, but many are out of date, out of print or difficult to locate.
One goal of the Wyoming Climate Atlas is to remedy this situation by providing, under a single cover, a comprehensive compendium of data on all facets of Wyoming's climate. Another goal is to acquaint the reader with the kinds of data which are available and how they can be obtained and properly interpreted.
Measurements made by several different organizations have been compiled and are assembled and summarized in the pages which follow. Most of the data presented in this atlas were obtained from completely new computations based on literally millions of individual daily and hourly meteorological measurements made throughout the state during the period of 1951 through 1980. At the time of writing, this is the same period used for the figuring of normal climatological values by the National Weather Service and the National Climatic Data Center. The data are presented in more than 200 maps, graphs and tables which are explained in accompanying narrative text. These explanations include words of caution and examples of the proper interpretation and application of the data.
The atlas is intended to serve as a data source and reference book. Although written primarily with technical applications in mind, clarity has been stressed in order to make the information useful to non-scientists as well as scientists. Most users will probably only consult selected portions of the book to find the specific information they require.
English and metric units are used in the text and figures. Whenever possible, graphs have a double set of axis scales, one for English units and one for metric. Most tables use English units to conform with standard practice for surface reports of weather and climate in the United States. Thus, the tabulated Wyoming data are easy to compare with similar data for other states, but comparisons with climate data from other nations is less convenient. A table of unit conversion factors is given in Appendix D.
Chapters 1 addresses the physical factors which govern climate: Chapter 2 discusses measurement locations and availability of data in Wyoming. Each subsequent chapter addresses separate, but not unrelated, climatic features such as evaporation, etc. Climatological data summary tables and graphs for more than 140 Wyoming towns are contained in Appendix A. In each chapter, information obtained or adapted from other publications is credited in the list of references which also serves as a valuable bibliography for further study.
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