Amazing icicles

I just learned from an article in the Washington Post, Icicles: A symbol of winter and a scientific mystery, that icicles share a common distance between the ripples that form along their sides, which is about one centimeter.  There is no understanding as to why this occurs with such consistency.

Curiously, it turns out that salt is common denominator for icicles being able to form these ripples.

Icicles on the sea caves at the Apostle Islands National Lakeshore