Valmiki Ramayana Aranya Kanda Sarga 52 Shloka 25
Original Shlokaतस्या भूषणघोषेण वैदेह्या राक्षसाधिपः। बभौ सचपलो नीलस्सघोष इव तोयदः।।3.52.25।।
1 source checked for this shloka
राक्षसाधिपः the lord of the demons, तस्याः वैदेह्याः that Vaidehi's, भूषणघोषेण by the tinkling ornaments, सचपलः along with lightning, सघोषः roaring, नीलः dark blue, तोयदः इव like raincloud, बभौ seemed.
The lord of the demons by the side of Sita, princess of Videha with her jingling ornaments looked like the darkblue raincloud with its lightning and thunder.