What is the most likely cause of an ice glaze coating trees, sidewalks, and roads on a winter morning?

The presence of an ice glaze coating trees, sidewalks, and roads on a winter morning is most often attributed to supercooled water freezing on contact. In conditions where the air temperature is below freezing, supercooled droplets can exist in liquid form. When these droplets come into contact with surfaces that are already at or below freezing, they instantaneously freeze, resulting in a smooth, glossy layer of ice.

This phenomenon can occur during various weather events, such as freezing drizzle or very light rain, where the droplets do not have enough time to freeze in the air and reach the ground as liquid. As they strike cold surfaces, they freeze instantly, creating a hazardous layer of ice.

In contrast, snow accumulation would typically not create a slick glaze; instead, it provides a fluffy, powdery cover. Fog freezing on contact is related more to ice formation on surfaces from atmospheric humidity rather than liquid droplets, and while rainfall can freeze rapidly, it is specifically the supercooled nature of the water that leads to this smooth icing effect directly upon contact.