Q1: Why does sleet bounce on pavement while freezing rain coats it instantly?
A1: Sleet falls through a deep sub-freezing layer of atmosphere close to the surface, allowing raindrops to completely solidify into hard ice pellets before reaching the ground. Freezing rain passes through a shallow cold layer, meaning the drops remain in a supercooled liquid state until they strike an unheated surface, breaking their surface tension and freezing on contact.
Q2: How much ice accumulation is required to pull down residential utility lines?
A2: Sustained ice accumulation between 0.25 and 0.50 inches creates enough dead weight to cause significant sagging and branch failure across distribution lines. Once radial accumulations exceed 0.50 inches, especially when coupled with wind gusts over 20 mph, structural failures of main cross-arms and commercial utility poles occur rapidly.
Q3: Will ordinary rock salt effectively melt pavement ice during an ice storm?
A3: Standard rock salt (sodium chloride) loses practical effectiveness when ambient air and pavement temperatures fall below 20°F (-7°C). For freezing rain and glaze conditions running colder than this mark, apply calcium chloride or magnesium chloride pellets, which generate heat as they dissolve and melt ice effectively down to -25°F.
