'Ambience', according to its dictionary definition, simply means 'surroundings'. It's generally used to describe the 'feel' of a place, rather than of a situation (as in your suggestion).
So, for example, this might be an appropriate use of 'ambience':
"The Good Pub Guide had described the Crown Inn as 'having ambience'. Neil hadn't understood the meaning. Now, as he entered the tap room, he placed his own interpretation upon that phrase. The pub certainly had 'ambience'. It had the ambience of a BNP meeting, playing host to the Ku Klux Klan, to support a speech by Oswald Mosley. The eyes that watched him, as he approached the bar, told him as much as the silence which had descended when he'd entered: This was no place for a black man to be".
Alternatively, a restaurant reviewer might write something like this:
"The ambience of the Taj Mahal is as far from the traditional flock wallpaper of Indian restaurants as it's possible to get. The walls are roughly plastered and totally undecorated. Customers are seated upon chairs, and at tables, which owe their design more to Copenhagen than to Calcutta".
Chris