Cholla Silhouette

I had an unfortunate encounter with a cholla last week -- it wasn't very tall, maybe 1/3 of the way to my knee, and I didn't see it at all. I walked straight into it, and all of sudden felt many very sharp pricks on my shin. I pulled the spines out of my jeans, but I had to use a pair of pliers to get them out of my boots. Ouch!

And that is why I almost always wear long jeans and boots when I hike. That encounter would've been very ugly with shorts and/or flip-flops.

There were zillions of contrails, in various stages of decomposition, in the sky today. I think they make the sky incredibly ugly. Why do they stay around for so long on some days, and not at all on others? Does anyone know?