New research suggests air pollution and high-rise buildings alter air flow and heat absorption, creating more rainHouston receives an average of 12cm more rain a year than its surrounding rural hinterland. And Houston isn’t alone. As well as being urban heat islands, rainfall data shows that the world’s largest cities tend also to be “urban wet islands”. Now new research shows much of this extra rain falls as light drizzle and that the urban wet island effect has strengthened over the last two d...