From Teflpedia

A circumstance (/ˈsɜ:.kəm.stæns/) is a semantic property of an event that expresses:

  1. The place where the event occurs.
  2. The manner in which the event occurs.
  3. The time in which the event occurs.
  4. The frequency that the event occurs.
  5. The reason why the event occurs and
  6. The result of the event.

In English, circumstances are expressed using adverbials. There are also specific circumstantial adverbs.