I can come up with many narratives for this. A post-apocalyptic building skeleton, with a wormhole forming... I wouldn't be surprised to see the Starship Enterprise fly through the hole.
Interesting comments... I've never thought of the cloud as a portal, but now that you mention it, I like that!
@awty ...The concrete structure is the lift over abandoned coal mine shaft. My goal is to get up inside the next time I'm in Japan. Luckily, I know some higher ups who will hopefully get me inside.
@MattKing ... I'll probably make a kallitype, followed by a carbon print. Most of the carbon prints I make form this series consists of coal dust. I still have a few lumps of coal from Manda (my favourite coal mine), that I need to mortar and pestle down...