Hi LollyMc,
Apart from one or two details in your post, I am in exactly the same position as you, same type of boss, same conditions, cant even see out a window to know if it's night or day. I've also got years of experience but am treated like someone not even at graduate level.
I agree with the posts above about speaking to your boss. I spoke to mine about the shouting, cranky, picky and strange attitude towards the employees. I did this in a structured way, through a couple of chats outside the office, where I had my points written down with specific examples to back them up. I put it to him that I was unhappy with the treatment I was getting and that I was becoming more and more demoralized, I made sure that it just came across as feedback and not an attack on his personality or anything like that because I was worried if it came across as agressive then things would just get much worse. Anyway, eventually he took on board some of the things I said, some others he completely disagreed with. We haven't fallen out over it, and he now wants to try some changes in the office.
Things probably won't change but I thought it was better to bring up these issues rather than beginning to hate the place and leaving in such a negative way. If things don't improve in the next couple of weeks, I will be handing in my notice regardless of whether I have a job or not (my boss knows this). My sanity is more important than a regular wage at this stage.
Best of luck.