harmatfagy

Harmatfagy is a meteorological phenomenon that occurs when frost forms on surfaces that are below freezing point, but the dew point is above freezing. This means that condensation, or dew, forms and then freezes. It is distinct from hoarfrost, which forms directly from water vapor in the air to ice crystals without an intermediate liquid phase. Harmatfagy typically happens in calm, clear conditions, often in valleys or low-lying areas where cold air settles.

The formation of harmatfagy requires specific atmospheric conditions. The air temperature must be at or below the freezing point of water (0 degrees Celsius or 32 degrees Fahrenheit), and the relative humidity must be high enough for dew to form. If the surface temperature is below freezing and dew forms, it will then freeze, creating a layer of ice crystals. This is often observed on grass, leaves, and other exposed surfaces.

Harmatfagy can have agricultural implications, as the ice can damage delicate plant tissues. However, it is generally less damaging than a hard freeze, which occurs when the air temperature itself drops significantly below freezing. The presence of harmatfagy is a sign of a radiative cooling event, where heat is lost from the ground to the atmosphere, leading to a drop in surface temperature.