Valmiki Ramayana Sundara Kanda Sarga 64 Shloka 23

वेगवन्तः swift, ते प्लवङ्गमाः those monkeys, महानादम् roared aloud, विनदन्तः noise, वातेरिताः driven by the Wind, घनाः यथा like heavy clouds, सहसा at once, अम्बरम् to the sky, उत्पत्य went up.

The swift monkeys roared aloud as though they went up the sky like thundering clouds driven by the wind.