From AMS Glossary
"The accumulation of snow in lumps under a ski runner, snow shoe, footgear, or a dog's pad. Balling occurs especially under conditions of high temperature and high humidity." [from Glossary of Arctic and Subarctic Terms (1955)].
Arctic, Desert, Tropic Information Center (ADTIC) Research Studies Institute 1955. Glossary of Arctic and Subarctic Terms. ADTIC Pub. A-105, Maxwell AFB, AL, . 90 pp.