I took these images in the parking lot as I was leaving work this evening.
Do you know what they are?
They're the pattern left behind in the salt by the teeny tiny six by four inch square bit of tire that your car rests on all day when it's standing still (x4, of course!). Different tires = different tread patterns. I had never noticed them before tonight, perhaps because it has been dark by this time of day for the past few months. Now that the days are getting longer, it's easier to notice things like these interesting designs underfoot.
The alarming thing was that in the time it took me to take these 3 images, which was maybe 30, certainly no more than 60 seconds, my hand was utterly frozen. I had to take my glove off to use the camera on my phone, but the wind was so very cold (minus 17C windchill factor) that even in that extremely short period of time, my hand was chilled to the bone. I put my glove back on, got in the car and started driving and it was literally five to ten minutes before my hand felt back to normal. Man, I pity the people working and living outside in weather like this, I really do. I don't know how they stand it!