hail
雹 centers on frozen precipitation that falls as pellets of ice: hail.
雹 combines 雨 (rain) with 包, which likely contributes the sound and the idea of something wrapped or enclosed, suggesting ice pellets wrapped in a storm.
Rain 雨 wraps around 包 like a package of ice falling from the sky: hail.
For ハク, imagine a hawk swooping down through a hailstorm: hawk -> ハク, and the hail pelts the hawk's wings.