URBAN WINDS

Wind Portrait of the Pacific Ocean Figure 4.6

General Atmospheric Circulation Figure 4.13a

Land-Sea Breezes Figure 4.18

Mountain-Valley Breezes Figure 4.19

Santa Ana Winds

Urban wind field

Wind Wind direction, speed and frequency will influence the building design including bracing requirements, roof and wall cladding selection, weathertightness detailing, building entry locations, window size and placement and provision of shelter for outdoor spaces.

Four categories of cities with increasing roughness length according to Grimmond and Oke(1999). The associated flow regimes (figure 6.3) are: isolated flow (low density: a, b, c); wake interference flow (medium density: d, e, f) skimming flow (high density: g, h, i) and chaotic or mixed flow (high rise: j,k,l)

Wind tunnel model of the New York Trade Centre (study by Drs.J.E.Cermak and A.G.Davenport in the Colorado State University boundary layer wind tunnel for L.E.Robertson of Worthington, Skilling, Helle and Jackson, 1964, with permission).