TEPCO cam 4 shows atmospheric distortion whereas TEPCO cam 1 shows clear skies. This discordance between the imagery is UNUSUAL and I remarked on it last time I saw it at my blog.
http://majiasblog.blogspot.com/2015/10/inconsistent-webcam-imagery-from-tepco.html
I am suspicious that webcam 1 has been manipulated since the roof was taken off (see The Asahi Shimbun here) to obscure emissions.