On an already cool, damp day, it takes very little extra moisture to obscure the field of view. In this case, the source was a steam vent in the Gunnuhver geothermal area, its well-defined plume of effluent wafting across the land to create this extraordinary visibility gradient at the surface. This doesn’t fit the commonly known fog types: radiation, advection, or precipitation. Instead it is directly generated by release of underground heat and moisture–geothermal fog.
6 WSW Grindavik, Iceland (10 Aug 14) Looking NNE
63.8191, -22.6845