The layout of a room will immediately cause different reactions in people, depending on how it has been set up. This can make or break a session if you are unaware of what to look out for. This includes the way seating is arranged, lighting, even whether curtains and doors are open or closed. Knowing some of the basics can help when a certain atmosphere is needed.

Sometimes in times of sung worship, you may notice that all of a sudden a certain 'ambience' has suddenly come about, which may be God working, but in a some instances can be just because of the style of music. Getting the balance between the two is a difficult thing, because on the one hand, you know that you want to get people to a certain place, so choose appropriate songs, Bible passages, noise levels, etc to bring that about. This can be a helpful thing to encourage people along, and to quieten a large crowd down before going into a time of more meditative prayer, but it's a fine line between that and creating a false feeling of God moving in a certain way when He may be wanting to go another. Being open to the Holy Spirit is always essential.

What I have written above is not to undermine that God does indeed work in amazing ways, and that this needs to be embraced in worship times. Situational ambience is a thing worth gaining understanding of as it is helpful for many sessions outside of a time of worship.