 the waliyya is the saddle and the waliha is a cloak placed over the saddle. so he likened the clouds in their intense blackness to the blackness of camels that have been covered with sackcloth. the rabab is a hanging cloud without a cloud above it. the poet said
و الولية البرذعة و الوليحة مسح يجعل فوق البرذعة. فشبه السحاب فى شدة سواده بسواد الابل وقد عليت بالمسوح و الرباب سحاب متدل دون سحاب فوقه. وقال الشاعر