Under what conditions is frost likely to form?

Frost formation typically occurs under clear, calm winter nights because several key conditions favor its development during this time. On clear nights, the absence of clouds allows for significant radiative cooling of the ground, causing surface temperatures to drop. Calm conditions, with little to no wind, enhance this cooling effect as there is less mixing of warmer air from above with the cooler surface air.

When temperatures fall to or below the freezing point, the moisture in the air can condense and then freeze upon contact with surfaces such as grass, leaves, or car windshields, leading to the formation of frost. This phenomenon is less likely to occur on warm and windy days, as warmer temperatures do not support frost, while wind can disrupt the cooling process by mixing warmer air with the cooler surface air. Additionally, conditions where temperatures exceed 10°C or where humidity is very high do not favor frost, as the temperatures are simply too warm for frost to form, and high humidity can lead to other conditions, such as dew.