Thunder rolled across the plains like the beating of a drum, lightning punctuating its rhythm with the crash of cymbals. Immersed in the roar of Mother Nature’s heartbeat, no one heard the gunshots.
These sentences are a perfect example of purple prose. The writer embellishes the exposition with tactile words, metaphors, and poetic rhythm.
The writer either wants to add literary voice or evoke emotions in the reader. But unless you write lit-fic, your voice needs to fit your genre (or break the rules well enough). As to evoking emotions, situations work best: throw your characters into straits so dire your readers do the crying for them.
The occasional purple sentence is okay. The above quote might work if surrounded by active narrative or dialogue.
But if this is your style, you need to do some heavy editing. Too much purple gets an auto-reject.