What is the main difference between radiation fog and advection fog?

Correct answer: Radiation fog forms by local surface cooling and advection fog by moist air moving over a cold surface

Correct answer: A. The key difference is the way cooling is supplied. In radiation fog, the ground loses heat, usually during clear and relatively calm nights. The air touching the cooled ground is chilled to its dew point, so water vapour condenses into tiny droplets near the surface. In advection fog, moist air moves horizontally over a colder land or water surface. Contact with that surface cools the moving air to saturation and produces fog. A is correct because it identifies local surface cooling for radiation fog and horizontal movement over a cold surface for advection fog. B is wrong because volcanoes are not the defining mechanism. C is wrong because neither definition restricts the fog to space, and radiation fog is not limited to the sea. D is wrong because both types involve condensation. Memory cue: radiation means nighttime heat loss; advection means air movement.