What are some examples of assonance in Act 3, Scene 5 of Romeo and Juliet?

Assonance is the repetition of vowel sounds and often provides a more melodious sound to a character's speech.  When Juliet describes the nightingale, she says, "Nightly she sings on yon pomegranate tree. / Believe me, love, it was the nightingale" (3.5.4-5).  Here, assonance occurs with the long "e" sound in Nightly, she, tree, Believe, and me.  It makes sense that Juliet's speech would be so musical in this moment because she is happy, but also because she, in part, describes the sound of the nightingale, whose voice is melodious compared to the lark's.  

Further, a few lines later, she says, "Yon light is not daylight, I know it, I" (3.5.12).  Here, assonance occurs with the long "i" sounds in light, daylight, I, and I.  Next, she says that the light "is some meteor that the sun exhales / To be to thee this night a torchbearer, / And light thee on thy way to Mantua. / Therefore stay yet. Thou need’st not to be gone" (3.5.13-16).  Here, the assonance once again occurs with the long "e" sound in meteor, be, thee, thee, and need'st.  She would be pleased by those things associated with night -- nightingales and meteors -- because she knows that Romeo will have to leave when daylight comes.  Therefore, when she describes the night, its sounds and its sights, she does so in quite a musical and euphonious way.  When she recognizes that it is, in fact, daylight, her speech loses much of its musicality.