adverbial clause

An adverbial clause is a clause that functions as an adverb. In other words, it contains subject (explicit or implied) and predicate, and it modifies a verb.I saw Joe when I went to the store. (explicit subject I)He sat quietly in order to appear polite. (implied subject he)According to Sidney Greenbaum and Randolph Quirk, adverbial clauses function mainly as adjuncts or disjuncts. In those functions they are like adverbial phrases, but in their potentiality for greater explicitness, they are more often like prepositional phrases (Greenbaum and Quirk,1990): We left after the speeches ended.We left after the end of the speeches.
See more at Wikipedia.org...

在复合句中作状语的从句,叫做状语从句(the Adverbial Clause).
访问 Wikipedia.org... 网页

part of a sentence which serves to modify verbs adjectives or other adverbs

副詞節, 動詞や形容詞や他の副詞を修飾するのに使われる文の一部

proposition adverbiale