On 21 December 2017, the Highlanders awoke to a beautiful, crystalline morning. There had been a bit of moisture in the air overnight, but not a complete fog. It got cold, too, and the surfaces of the plants, benches, fences, signs and so on actually got below freezing. When the moisture in the air increased, and then came in contact with those solid, freezing surfaces, ice crystals formed. Formation of hoarfrost is similar to — but certainly different from — the process of dew formation. In the latter instance, dew (drops of liquid water that condense out of the water vapor in the air) form on a surface when that surface is cool, but above freezing (32°F/0°C). If the surface that the water vapor condenses on is too cold, though, you get SOLID water: ice!