In urban meteorology, questions of how spatial scales of surface morphology interact with the structure of the atmospheric boundary layer, and how that interaction affects the transport of heat, mass and momentum between the two, are perhaps more important than in any other subfield of boundary layer meteorology. A conceptual framework and methodological tools to quantify notions of spatial homogeneity, surface variability texture and spatial representativeness are illustrated at the hand of examples that grew out of the "Oke School" and are now commonly applied in observational and modelling applications over urban, agricultural and forested areas.