Recently I stumbled upon a funny picture of a frozen water fountain. The frozen fountain resembles a mushroom:
The longer I look at this picture, the less I understand how such a shape can even start growing.
While there is still flowing liquid water, the only place where this icy shape can start to grow is the metal border at the bottom. But then, how is it growing there? Is the ice forming a border first, growing upwards and finally freezing to the middle?
And how and when did the "mushroom head" grow? I assume the water was in permanent flow.
It just hit me that the "mushroom head" was probably not shaped by the water stream becoming a membrane, but by the metal shape below. The relief of the "head" seems to match the relief of the metal below. But then again, how was the "mushroom head" lifted once it was frozen? If still water in the tube was freezing and expanding, was that really enough to lift so high?
I can't explain it. Therefore my question:
Can somebody explain how this ice shape has been formed, out of flowing water, metal and cold?