To alleviate tension, often in a group setting. Similar to the phrase "clear the air." I know my parents are still mad at me for missing curfew, so I'm going to try to clear the atmosphere this morning by apologizing profusely.
something that you say to describe a situation in which everyone is feeling very angry or nervous and you feel that something unpleasant could soon happen There was a lot of tension between Diane and Carol; you could cut the atmosphere in that room with a knife.