What is one idea or concept that a rain
cloud could symbolize?

depression. sadness.  

Explanation:

The Rain Cloud Symbol carried very high importance. This was because it carries the element of water and it is one of the most vital amongst all elements as it carried the sustenance of life. The basic things which the Rain Symbol signifies are renewal, fertility, and change.

the sentence that avoid faulty coordination is:

culture, which is well represented in philadelphia, plays a major role including theatre, music, and the visual arts.  

faulty coordination occurs when the writer gives equal importance two different ideas (clauses) which in fact are not equivalent. in order to correct a misplaced clause or idea, the writer can place less important or emphatic ideas in a relative clause as in the previous sentence.  

merry christmas to you, too. may god be with you all in doing your work and just living a great life in general! < 3