Ice Pattern Mono

I always been fascinated by the patterns that occur in shallow puddles when there is a sharp frost overnight. Yesterday morning there were several puddles like this in the field as I took the dogs a walk. I tried to find out more about the reason for this phenomena on the internet but found the explanations quite complicated and therefore rather than paraphrase i thought it would be better copy and paste the one I found easiest to understand.

'How various ice features form, change shape and melt is rarely straightforward and sometimes quite confounding. Factors such as water purity, the rate of cooling, the preferred growth of ice in crystalline planes, etc., all play a role. 

The shallowness of this puddle suggests that it rapidly froze; only a thin water layer remained below the puddle. Then the fast-falling temperatures likely caused the ice to contract, which produced the cracking. Continued cooling widened the cracks. The ring pattern shows that the main direction of the stress force was radial, but the scalloped pattern along the rings shows that some stress varied with angle around the center. The small amount of water that didn't freeze rose into the cracks due to the hydrostatic pressure of the ice above and capillary action. Water in the rings then froze and expanded, and as it did it widened the rings and also directed the remaining small amount of liquid to the top of the ice. The slight bulges on the bottom of the rings were remnants of its last contact with the deepest water. In other words, the unfrozen water at the bottom of the puddle was, in essence, pushed and suctioned into the cracks.'