I've been thinking about this question for a while. This is my definition of what makes a sentence lyrical:
1. The use of metaphors:
So I walked back to my room and collapsed on the bottom bunk, thinking that if people were rain, I was drizzle and she was hurricane. ― John Green, Looking for Alaska
2. The use of words related to nature:
"When I closed my eyes, the scent of the wind wafted up toward me. A May wind, swelling up like a piece of fruit, with a rough outer skin, slimy flesh, dozens of seeds." ― Haruki Murakami Blind Willow, Sleeping Woman.
3. The use of rhythm (alternating short sentences with long sentences):
"Memory is a funny thing. When I was in the scene, I hardly paid it any mind. I never stopped to think of it as something that would make a lasting impression, certainly never imagined that eighteen years later I would recall it in such detail. I didn't give a damn about the scenery that day. I was thinking about myself. I was thinking about the beautiful girl walking next to me. I was thinking about the two of us together, and then about myself again."
I would like to hear other definitions, or to know whether I'm mistaken.