This is a reference to a Chinese poem by Sugawara no Michizane in the Wakan rōei shū – Shunzei is referring to the Chinese characters used to write the words arare (‘hail’) 霰 and tama (‘gemstone’) 玉 rather than the words themselves: 「麞牙米簸声々脆、竜頷玉投果々寒」. In Rimer and Chaves’ translation (1997, 120), the poem is:

The roebuck’s teeth, rice grains in a sieve,
every sound so crisp;
from dragon’s jaws, peals are tossed,
every kernel cold,

This poem is on the topic of ‘Hail’, even if the word, or character itself does no appear in it.