“Appropriate” emotion is nothing more or less than emotion that is correct for the situation and in correct proportion to the evoking circumstances. At the extremes
of emotional expression, there tends to be a good degree of cultural consensus both concerning which emotions (if any) are desirable and on how (quantity, quality, and duration) these emotions ought to be felt and shown.
Shields, S. A. (2005). The Politics of Emotion in Everyday Life:" Appropriate" Emotion and Claims on Identity. Review of General Psychology, 9(1), 3-15. doi: 10.1037/1089-26188.8.131.52.