I wonder if anyone has come across the word udagagni, or some other compound meaning 'northern/upward fire', other than in the ritual context of sacrificial fires? I am not at all sure what it means, but it is mentioned (in the astrological work Hāyanasundara, v. 166) together with lightning and thunder (and enemies):

syāt ketuyutadṛṣṭaś cet kujo vidyudbhayaṃkaraḥ | syān meghagarjanād bhītiś codagagniripor api ||

(The Sanskrit of the HS is not very elegant, and I don't think udagagniripoḥ is anything more complicated than a dvandva, despite the singular inflection. It could even be a scribal error för udagagne[ḥ] ripoḥ.)

Thanks in advance for any suggestions,

Martin Gansten