Urban wind speeds continue to drop as high-rise buildings change city airflow

UPDATE - follow-up to Letting the wind flow freely is the secret to cooling our cities: Ground-level wind speeds in cities continue to slow down due to high-rise buildings and dense urban structures, worsening heat stress and trapping pollution.

Urban Stilling

Wind speed near the ground has dropped globally in a trend known as terrestrial stilling since the 1980s. Amruthraj M.N., a consultant at the Indian Institute for Human Settlements in Bengaluru, notes that this drop happens mostly around 10 metres from the ground where pedestrians walk. Meteorologist Aaron Serre explains that dense buildings and concrete surfaces cause turbulence and increase friction, which slows down winds.

Building Design

Unplanned high-rise buildings, high compound walls, and podiums block natural wind corridors in Indian cities. When winds hit tall buildings, they can create the Venturi effect in narrow spaces or the downdraught effect by pushing air downwards into strong gusts. Prasad Vaidya of IIHS says that while direct links between urban stilling and city warming are hard to prove, unplanned buildings clearly add to heat stress.

Context

Urban microclimates are heavily shaped by physical structures that alter natural air circulation and surface temperatures. Understanding these local wind patterns helps planners design better ventilation systems to keep densely populated areas liveable.