Namib Desert - Climate

Climate

The Namib's aridity is caused by the descent of dry air of the Hadley Cell, cooled by the cold Benguela current along the coast. It has less than 10 mm (0.4 inches) of rain annually and is almost completely barren. Besides rain being scarce, it is also hardly predictable. The western Namib gets less rain (5 mm) than the eastern Namib (85 mm). This is due to several factors. Winds coming from the Indian Ocean lose part of their humidity when passing the Drakensberg mountains, and are essentially dry when they reach the Namib Escarpment at the eastern end of the desert. Winds coming from the Atlantic Ocean, on the other hand, are pressed down by hot air from the east; their humidity thus forms clouds and fog. Morning fogs coming from the ocean and pushing inwards into the desert are a regular phenomenon along the coast, and much of the life cycle of animals and plants in the Namib relies on these fogs as the main source of water.

The dry climate of the Namib reflects the almost complete lack of bodies of water on the surface. Most rivers flow underground and/or are dry for most of the year, and even when they are not, they usually drain into endorheic basins, without reaching the sea. The Swakop and the Omaruru are the only rivers that occasionally drain into the ocean.

All along the coast, but mostly in the northernmost part of it, interaction between the water-laden air coming from the sea via southerly winds, some of the strongest of any coastal desert, and the dry air of the desert causes immense fogs and strong currents. It causes sailors to lose their way; this is testified by the remnants of a number of shipwrecks that can be found along the Skeleton Coast, in northern Namib. Some of these wrecked ships can be found as much as 50 metres (55 yds) inland, as the desert slowly moves westwards into the sea, reclaiming land over a period of many years. Benguela's El Nino (similar to the Pacific event in its environmental change in the seas) spreads from the Kunene estuary southward to, on occasion, south of Luderitz. Warm waters with depth and associated water flows from northwesterly direction were first fully catalogued by Sea Fisheries researchers, Cape Town (L V Shannon et al.). The research noted the positive effect of Benguela\'s El Nino on the rainfall of the interior. Rainfall records also show positive values variously across the Namib, Desert Research Station, Gobabeb for instance. This event recurs approximately mid-decade (1974, 1976, 1994, 1995 and 2006 are recent examples)