What is hoar?

Hoar generally refers to a coating of frost or ice crystals that form on surfaces exposed to cold and humid air. It is formed when water vapor in the air condenses directly into ice crystals without first becoming liquid. The term "hoarfrost" is often used to describe a particularly dense and intricate layer of frost that resembles feathers or needles. Hoar can form on trees, grass, and other vegetation, creating a beautiful and delicate wintry landscape. However, it can also be hazardous to drivers as it can cause roads to become slick and slippery. Hoar can also form in caves and other underground spaces, creating unusual and striking ice formations.