Snow and ice on roofs - icicles and climate change

Snow and ice is a typical winter problem. Snow accumulates on roofs and icicles can hang at the eaves. The downfall of icicles can kill people. To prevent that we need to look at architecture, meteorology, glaciology and building physics. The physical theory for growth of icicles and their geometry is described. The spacing between icicles is explained. To get icicles to grow we need melting water comes either from solar radiation or heat loss from buildings. Two cases with icing on roofs are shown. Rules for reducing the risk for snow and ice problems on roofs are described. The effect of climate change on icicles is discussed