Brihat Samhita
चलिताचलवर्ष्माणो गम्भीरविराविणस् तडिद्वन्तः । गवलालिकुलाहिनिभा विसृजन्ति पयः पयोवाहाः ॥ ३२-१७ ॥
Clouds like so many moving mountains, roaring aloud, attended by lightning and black as the horn of a buffalo, as the bee and the black cobra, will yield abundance of rain.
english translation
calitAcalavarSmANo gambhIravirAviNas taDidvantaH । gavalAlikulAhinibhA visRjanti payaH payovAhAH ॥ 32-17 ॥
hk transliteration by Sanscript