One of the unique features of our westward orientated horse riding safaris is that we traverse one of the most unique fog deserts in the world - the Namib. Home to more endemic species than any other desert, the Namib has many delightful surprises to those who have the eyes to see the extraordinary.
Situated in the sub-tropics, Namibia’s generally warm conditions disperses all moisture from the air resulting in arid conditions, particularly along the coast. The Namib would however be much more arid if it were not for fog precipitation which has resulted in some extraordinary desert adaptations.
The unique life in this desert depends on the frequency of this life-giving fog. Occurring 60 – 120 days per year it produces five times more precipitation than rain and is much more predictable.
Image left: The extent of coastal fog on the Namibian coastline
What is fog and how is it formed?
Fog is formed when moisture laden air is rapidly cooled resulting in condensation into fog or low-level clouds. The cold upwelling Benguela current that runs in a northerly direction along Namibia’s coast is responsible for the cooling.
Image left: Arriving on a foggy beach in Swakopmund, Namib Desert Safari (advective or ground-level fog)
It is the nutrient rich Benguela Current which produces the huge biomass of plankton and fish which in turn lead to a large variety of coastal desert fauna – seals, birds, jackal, hyena and even lion.
Fog occurs either as advective or intercepted. Advective fog is less than 200 m high and extends no more than 15 km inland depositing moisture on any surface it touches, including plants the bodies of ‘fog-basking’ creatures such as Darkling beetles and gecko’s.
Image below: High fog or low stratus cloud on Damara Elephant Safari.
The iconic Welwitschia which we encounter on both our Namib Desert and Damara Elephant riding safaris are also able to harvest all their moisture needs from fog and provide moisture, food and shelter to many desert creatures.The Welwitschia is a good example of plants able to harvest fog
Intercepted fog or low stratus cloud can extend inland as far as the escarpment. Where the fog intercepts the land gradient – generally 60 km from the coast – precipitation on any object in its path can be over 1 litre per fog event. Nets designed to harvest fog are able to extract up to 15 litres of water per square metre during one fog event. Anyone who has experienced a night out in foggy conditions – as we sometimes do on our safaris – knows how incredibly wet everything gets despite the aridity of the desert. And how quickly it dissapears again in the dry air.
Image left; Darkling beetles do headstands on dune crests allowing water to roll down to their mouths
Fog is partially responsible for the more than 1000 shipwrecks which litter the notorious Skeleton Coast. Many an incredible tale relates the extraordinary feats of survivors who have walked hundreds of km in search of help. No doubt the life-giving fog aided them in making these challenging journey’s.
Lighthouses on Namibia’s coast still bear testament to the challenges of navigating this wild coastline.
Image right: Walvis Bay Lighthouse