The book “Cloud Studies” was published in 1905, over a hundred years ago.  It was written by Arthur W. Clayden, M.A., Formery principal of University College, Exeter, UK. The book is available in PDF form since it’s out of copyright:

http://contrailscience.com/files/Cloud_Studies.pdf

But the images are rather low quality, so I scanned them in from my copy of the 1925 edition (mostly the same photos), and I present them here:

http://picasaweb.google.com/Uncinus/CloudStudies1905And1925

It’s interesting that there are some clouds there that you might think look unnatural, or man made.  But these photos were taken before powered flight was invented.

So if you are ever looking up at the sky, and you see a cloud that looks a little odd, and you are wondering if this is a recent phenomenon, then have a look back at what clouds were like in 1905.  You’ll probably find your cloud here.