frost

A drop in air temperature to a value equal to or below 0°C, corresponding to the freezing point of pure water at sea level under normal pressure conditions (P = 1013 hPa). Depending on the mechanism responsible for the temperature drop, frosts are divided into two main types: 1) radiation; and 2) advection. In agriculture, a distinction is also made between white frost (hoarfrost) and black frost, depending on the appearance of the ice accumulated on the ground and vegetation, which has different consequences for crops.