In this chapter, airflowFlow over hills was assessed over modified surfaces, mainly corresponding to urban areas, hills, or transitions between surfaces with different roughness, land uses, and ambient temperatures. This surface heterogeneity that leads to the development of an internal boundary layerInternal boundary layer, including sublayers, with a determined height and influence length or fetchesFetch were analyzed. In the same way, the variation of surface temperatures leads to internal thermal boundary layers with estimable heights. Airflow patterns over isolated arrayed building elements were assessed with turbulent changes in verticalVertical profiles in the internal boundary layer velocity profiles, typical wakes or cavities, or horizontal wrapping horseshoe vortices in the context of urban heat island or stratification effects, with implications in items as distinct as atmospheric thermal regimes or pollutant dispersion. The main airflow patterns over isolated or grouped hills were discussed, with an analysis of air circulation around and over hills under different stability conditions characterized through Froude number variation. Finally, a discussion was carried out of the dynamics of specific atmospheric case studies, such as katabatic windsKatabatic winds or Foehn and Bora-type descending flow in hills under inversion conditions, with potential relevant theoretical extrapolations.