I would have to say the first transition word that signals the cause and effect pattern in the paragraph is the word causing. I concluded this by observing the structure of the text. The text begins with a question: (1) paraphrase: "Why does lightning make such a loud sound?" The text then immediately explains the cause of a lighting bolt: (4) paraphrased: "causing the temperature of the surrounding air to rise greatly." After explaining the scientific basics, the text goes on to explain the effect of the cause: sentence (6). Another hint that causing is the first transition word is the fact that the begining of sentence (5), a dependent clause, is split by a comma from the independent clause after it. Most transition words are separated from clauses/phrases with a comma.