It sounds like the title of a murder mystery, The Bubbles in the Brook. When I look at them, it’s a mystery to me how whole bubbles can get frozen into the ice in fast moving water. Turns out bubbles are, like most everything else, just a wee bit more complex than you thought.

Were they to have occurred in pond or bog water rather than in the stream we’d have assumed they are caused by methane from rotting plants on the bottom. The gas moves up through the freezing water ever more slowly, until finally the water pressure and that in the rising bubble are even and the hole thing sets like sugar syrup at the hard crack stage. The physics is some combo of the methane being lighter than water and thus rising versus the difficulty of doing so against water that is allowing less and less movement as it gets colder –sort of like Trump followers it just don’t want to step aside – and an equilibrium between the expanding forces of the methane bubble and those of the water turning to ice pushing against them. Get is just right and voila: stilled bubbles – themselves full of of stinky gas also like Trump followers.

Because the ice in the body of water keeps getting thicker and the gas still releases, this sometimes looks as if there’s a party on the bottom creating a whole stack of bubbles, perhaps telling a story of an icy evening in the dark under there. You can read about it here and if you google “bubbles in ice” you get some pretty amazing stuff like in this screen shot (those are not mine, in case you was wondrin’).

But that’s not what we have in the brook. These are bubbles in ice that forms in fast moving water. They have more to do with the bubbles in the ice cubes in your freezer than with rotting plants on the bottom. Which makes sense because there aren’t a whole lot of rotting plants on the bottom of the brook – that’s mostly stone doing its best to look incredibly handsome and colorful there at the bottom tumbling around together and getting rounded in the process, like Sarah Palin’s daughter.

The physics here is quite a bit tougher to understand than that of the rotting plants, for me in any case. When I start looking at it I get stuff like this page which asks whether those bubbles are at higher pressure than the atmospheric air surrounding the ice. Clearly it is not a hot topic (citations from 1961) but some folks have been walking around on the ice asking themselves the kind of question that won’t leave me alone when I am kneeling at the edge of the brook, nose on the ice, my pal behind me set at watch so our combined furry tumbling dog ball won’t bowl me into the drink. At least I hope he’s watching, chances are his nose is in the ice also. “How did this get here?”

Not to withhold the small article about the ice cubes which says that the dissolved air in water gets pushed out of solution when the ice freezes—ice doesn’t hold air in solution or at least less of it – which kind of surprises me if you look at ice crystals that look like so much scaffolding and lotsa space in between. In any case the idea is that water expands when it freezes and thus the ice that is sharing space with the water has less space and gets pushed together into a small bubble. Now that reminds me more of Clinton and Sanders, although who the air is and who the ice is a matter of opinion. The reason this type of bubble doesn’t say sayonara and waltz off into the air above either is that the ice is freezing in from the outside, particularly the air above, and the air gets more and more trapped in the bubbles in the ice. Same entrapment as with the pond scum, cleaner result.

Ah, it’s so much fun to take potshots at politicians. You could also simply enjoy the photos. If you click on one you get the album larger than on this page.