The formation of ice on the ground, on plants, or on structures near the Earth's surface as a result of the drop in air temperature to lower than 32°F (0°C) and the presence of water vapor or liquid water in the air. The causes of the cooling, and the types of ice that form, can be quite varied, depending on the existing meteorological factors. Frost can have serious impact, with the main effect being in agriculture, but transportation and other areas are also affected.