APPENDIX A (continued)
Gap Effect. When a building of five stories or more is elevated on
columns or has an open passageway through it, air forced through the
opening(s) creates a channel of intensified wind in the opening and on its
downwind side (see Figure A-12).
Pressure Connection Effect. Pressure connection effects develop as
the wind approaches parallel rows of offset buildings, creating suctions
between them that draw in downdrafts from exposed windward faces and create
transverse flows along the ground into the wake regions (see Figure A-13).
The intensity of the effect varies with building height, with taller buildings
producing more intense effects. The effects intensify further if the
crossflow channel is narrow and regular.
Channel Effect. A street or other open space lined with tightly
grouped sets of buildings can tend to channel the wind if the space is long
and narrow (less than three heights) in relation to the heights of the
building which bound it (see Figure A-14).