Under what conditions does frost typically occur?

Frost typically occurs during clear and calm nights because these conditions allow for effective radiational cooling. On clear nights, the heat from the Earth's surface can easily radiate into the atmosphere without being trapped by cloud cover. Calm conditions further enhance this cooling effect since the air is not mixed or agitated by wind, allowing temperatures to drop significantly near the ground.

As temperatures dip to the dew point, moisture in the air can condense and freeze on surfaces, leading to the formation of frost. In contrast, cloudy nights tend to keep surface temperatures warmer due to the insulating effect of clouds, while windy conditions disrupt the cooling process by mixing warmer air with cooler air near the surface. Cold but sunny days are generally not associated with frost formation since, during the day, solar radiation warms surfaces, preventing the temperatures from dropping enough for frost to develop.