Foggy morning

Autumn brings us foggy mornings. In southern and western parts of Finland every fifth morning in average is foggy

The most common fog type in autumn is radiation fog. It is formed by the cooling of land after sunset by infrared thermal radiation in calm conditions with a clear sky. The cooling ground then cools adjacent air by conduction, causing the air temperature to fall below the dew point, forming fog. Radiation fogs usually doesn't last long after sunrise.

The other common autumnal fog is evaporation fog. It most often appears when the air begins to chill before bodies of water do. As the cool-air layer closest to warm water begins to heat up, moisture from the water below evaporates into it. This air then rises into the colder air above, cools, and water droplets condense into fog. 



+17°C, foggy morning, cloudy day, sunny evening