Spiral Pattern on an Icy Puddle
February 22, 2023
Photographer: Mark Hendrickson
Summary Authors: Mark Hendrickson; Jim Foster
I’ve have seen concentric ice rings in puddles, but this is the first true spiral I’ve observed. This photo was taken about 17 miles (27 km) northeast of Payson, Arizona on January 21, 2023. The overnight low was 18ºF (-8 C), and at the time of the photo the temperature had climbed to 28ºF (-2 C). The surface of the puddle was about 2 ft (.6 m) across and was completely frozen. It's very likely that the ice didn't reach the bottom of this little puddle.
A number of factors can lead to odd patterns on icy surfaces. Note the fractures (white lines) in the ice at left, in the only ring not part of the spiral formation. The next ring starts the actual spiral. So, it seems that there was an initial sheet across the puddle, and when the ice became sufficiently thick (perhaps a few mm) only one more crack formed. With just a single crack, as the water beneath transferred to the ice and shrunk (contracted) toward the center, the crack grew and spiraled inward. However, exactly how these spirals formed is still a bit of a mystery. Thanks to Steven Arcone and Doug Stith for their help with this.
Payson, Arizona Coordinates: 34.2309, -111.3251
Related Links:
Explaining Ring Patterns in a Frozen Puddle