This study deals with human comfort expressed in a physio-climatic classification. Four physiological and psychological reactions of man to temperature, relative humidity, wind chill, and solar radiation are combined into two nomograms from which average human reactions can be deduced. Comfort and Wind Effect Indices are applied to meteorological data of the conterminous United States for July and January, daytime and nighttime, respectively. Maps combining both indices for July apply the classification on a larger scale (Southern California), and on a smaller scale ( U S . ) . A map of annual physio-climatic extremes synthesizes in generalized form how man tends to feel in various areas on a yearly basis. Thus, a three-step system results which attempts to revise certain conventional notions about comfort regions. No paradoxical distributions are apparent and the classification seems limited only by the availablity and reliability of data. The scheme is applicable to any dimension: time or region, and is considered a contribution to medical geography, climatological education, tourism, military geography, housing, clothing, and a general analytical tool, introducing greater precision into geography.

A comparison was made between the resultant surface temperatures and sensible heat fluxes of building interfaces calculated by steady-state and transient (implicit) methods. Both procedures used identical environmental (summer and winter) input. For exterior conditions, the results indicated that the correlation between the two methods is sufficiently large, enabling them to be used interchangeably for the spatial analysis of urban canopy layers of entire cities. Using a steady-state approach as a surrogate for unsteady conditions, computer resources can be saved up to a factor of ten. An urban energy budget model (URBAN 3) has been used to demonstrate that the distribution of sensible heat flux and net longwave radiation -the prime causes of urban heat-island generation -was far from the homogeneity assumed in many macroscopic models or even some street-level studies. The individual emanations of reradiation and sensible heat flux showed different diurnal and spatial patterns. Under the input scenarios used, daytime heat islands assumed a 'doughnut' shape in the inner city. It is believed that many of the lower boundary conditions used in macroscopic numerical models are inadequate in light of this study.

Climatology is reviewed and redefined in terms of relevance to geography, and a programmatic statement for future research is presented. Instead of enumerating substantive areas, physical geography is defined and ranked according to five levels of methodology and attendant philosophy. The essence of geographical climatology is the analysis and description of process-response systems of importance to mankind occurring within the planetary boundary layer, interface, and substrates. The future of a climatology useful to geographers appears to lie in the numerical modeling of such systems.

A model which attempts to simulate urban absorption of solar radiation is concerned with direct solar radiation, diffuse sky radiation, diffuse radiation reflected by buildings and streets, and the shortwave energy absorbed by typical urban structures. The ratio between solar radiation absorbed by three-dimensional building-street systems and two-dimensional horizontal surfaces under cloudless conditions indicates that cities undergo great variations with latitude and season. High structure systems absorb more than six times the radiation of nonurban plains. Shading effects can create absorptance less than that of a level surface. Observations at street level may lead to erroneous conclusions concerning the energy input for the total urban interface. The examination of a circular synthetic city with varying latitudinal radiation responses indicates that daytime urban heat islands are migratory phenomena and probably influence convective air circulation in the city, that downtown areas often absorb less energy than the periphery of the inner zone, and that the mere existence of a city is sufficient to generate daytime heat islands. KEY WORDS: Building climatology, Solar radiation, Urban climatology, Urban heat islands.HROUGHOUT history man has often T modified his climatic environment. Urbanization has brought about the most radical changes. Modern cities have developed with little or no regard for the climatic modifications created.l The city has an infinite number of microclimates that are intimately linked to the composition of its surfaces and the relationships of its structures. This urban-atmospheric system is interdependent, and climate cannot be treated independently of the city. Microclimates created or destroyed by the shade effect of tall buildings are a simple example.2

An intercomparison of the surface energy budgets from three urban climate models was made to assess the comparability of results, and to evaluate the surface energy fluxes from each model. The three models selected spanned the continuum of approaches currently employed in the treatment of the effects of urban geometry. The first model was an urban canopy-layer model which explicitly examined urban canyon geometry. The second model treated the city as a warm, rough, moist plate but included greatly simplified parameterizations of urban geometry. Neither model included a dynamic link to the urban boundary-layer. The third model was a one-dimensional urban boundary-layer model which utilized a simple warm, rough, moist plate approach but included a dynamic coupling of the urban surface layer to the urban boundary-layer.Results showed considerable disagreement between the three models in regards to the individual energy fluxes. Average rankings of the energy Buxes in terms of comparability from high-to-low similarity were:(1) solar radiation, (2) sensible heat flux, (3) conduction, (4) latent heat flux, (5) longwave re-radiation, and (6) longwave radiation input. In general, the urban canopy-layer model provided more realistic results, although each model demonstrated strong and weak points. Results indicate that current urban boundarylayer models may produce surface energy budgets with lower sensible heat fluxes and substantially higher latent heat fluxes than is supported by field evidence from the literature.