The formation of fog is encouraged by the air inversion caused by the Benguela current, and is a characteristic feature at the coast. In the early mornings the south westerly winds drift the fog inland. It usually extends for about 50 km inland for the length of the Namib, but occasionally fog occurs up to 100 km inland. Fog reaches NamibRand approximately 10 - 20 days of the year during the winter months. Unlike the ecology of the coast, none of the fauna and flora of NamibRand are dependant on moisture from the fog. Fog at the coast is usually only of short duration, rising temperatures from the interior have mostly dissolved it by noon, even so, fog-water precipitation is the dominant moisture source over western parts of the desert.