Author: Mary Knapp

Little white pieces of ice are falling from the sky. Is it hail or sleet? Size isn’t the only factor. The critical difference is layers. Sleet is formed by a frozen raindrop, or a refrozen melted snowflake, resulting in a solid sphere of ice. Hail, on the other hand, typically consist of layers of ice that form as core of the hailstone passes through various layers of the thunderstorm. Hail can get quite large. For a long time, Kansas held the record for largest stone in the US from Coffeyville, KS which had a diameter of 5.7 inches and a circumference of 17.5 inches and was observed on Sept. 3, 1970. In 2003, Nebraska broke the record when a hailstone with a 7-inch diameter fell in Aurora. The largest officially recognized hailstone on record was one which fell near Vivian, South Dakota on July 23rd, 2010. It measured 8.0” in diameter, 18 ½” in circumference, and weighed in at 1.9375 pounds.

Figure 1. Hail layers (WDL archives)

Mary Knapp, Weather Data Library