Ice and snow in downtown Luoyang melted away last weekend. But thanks to the previous freezing and moist weather, rime ice can be appreciated in Louyang's mountainous areas. Rime ice occurs when sudden cold weather forces fog to freeze into ice crystals on tree branches and other objects. The beautiful rime ice isn't seen often as it requires very specific moisture and temperature conditions before it can form.
Source:
http://english.cri.cn/6566/2015/02/15/44s866465.htm
