I would like to find other description of the atmosphere of a scene rather than just using the word 'tense.' Instead of writing, "The atmosphere between Bill and Bob is tense." What other ways would there be to describe what it feels like to be in the scene?
It would rather depend on how you want to describe it. You can choose to describe from the point of view of either of the characters or from a third person narration. You may even describe as the author.
Like (assuming some situation where two friends have fought) -
Author's point of view - The situation had never been worse for Bill and Bob. They both seemed to be in a fix in their current situations, neither could break out of it nor resolve it. The anger and egos prevented a happy reunion.
Third person point of view - There seemed to have a cold war begun between Bill and Bob. Though once good friends, they now couldn't bear to come in any form of contact with one another. It was not that they didn't want it. Having known them for years, I know that each wanted the good for the other but the times had changed and so had the perspectives.
From Bob's point of view - The past week has been very difficult. The worse of all is that when you need a friend, that friend is not there. It is simple to fight an enemy but difficult to fight a friend. I just don't see what has gone wrong with Bill. A matter of such insignificance has been made of utmost priority and the person known to reason out of things is just making some self importance issues.
Personally, I think atmosphere should always be illustrated (so to speak) in the action.
If the situation that led to the tension is known, one could have a couple of scenes where Bill and Bob interact tersely (or not at all). Having read the event that kickstarted the tension, it's easy to just 'see' that tension lingering in casual actions and dialogues.
If the situation that led to the tension is not known, and especially if the characters are not the main ones (so that a reader can't promptly tell they're acting particularly cold towards eachother), then one can have the same terse interaction which, in this case, will lead to someone commenting in the lines of "those two look like they're stuck in a cold war or something".
If you really must have a one liner, I'd suggest something that one might say in one's real life, in order to make the statement more natural sounding. I mean, if you have two friends fall out and you witness their coldness to eachother, how will you describe it? I'd never say 'the atmosphere is tense between those two', but might say 'they're barely on speaking terms' or use an idiom (sorry, I have a couple of idioms I'd use in my native language, but I can't think of any in English right now).