Living in an older home with single-glazed windows, I have grown used to seeing intricate patterns of frost on the panes each winter. However, I was truly impressed by a twining vine-like pattern that appeared this January (see Photo), and I would love to know how it came about. The vine-like shapes formed in a 20-by-30-centimetre section of the window and were surrounded by standard snowflake-shaped frost. The 鈥渧ines鈥� were 1 centimetre wide with small dots running up the centre, and they twisted about each other with leaf-like shapes sprouting from the sides. The photo shows a section measuring about 6 by 10 centimetres. It had been a particularly cold day (-20 掳C) and the sun was shining on the window. My wife suggested that the sunlight shining through the branches of a tree 2 metres away had caused this, but there were no distinct shadows visible on the window at the time.
Ken Zwick, Neenah, Wisconsin, US