A simple sentence consists of only one clause. A compound sentence consists of two or more independent clauses. A complex sentence has at least one independent clause plus at least one dependent clause. A set of words with no independent clause may be an incomplete sentence, also called a sentence fragment.
“The barometer of confidence soared.” and personifies confidence with the motion of soaring. This allows for the audience to comprehend that their confidence is strengthening and being lifted by comparing it to something relatable to human behavior.