Thanks Douglas and Tom.
The last couple of times I visited Yellowstone, I was looking especially for backlit steam vents in interesting places. This was- I thought- one of the best I found.
Charlie
Thanks SRudy, Cheryl, Hoser and Lazlo.
The vertical lines are mostly trees (thin lodgepole pines).
Because of the backlight, some of the shadows from the trees are noticeable. And the fog filtering through the trees is of varying thickness- causing some trees to look darker than others.
Well, that's my best guess .
Charlie