Stopping to look at ice and icicles this year has really made me wonder 'how?'  The physics of ice formation appears to be infinitely variable, which I guess makes sense since there are a lot of variables involved; salty or fresh water, sudden or chronic cold, fluctuating temperatures, flowing, falling or still water, etc.  

Look at these ripples, for example!  How did the circles get there? How did the first ripple take shape?  Why is there a gap between the rows of ice ripples?  

Why don't all ice walls end up this way, one giant ice-blob?

What planet are these found on?

So many shapes and patterns!  

What is the weirdest icicle shape you've ever seen?