On the whole, the Namib Desert in Southern Africa doesn't see much rainfall. To stay alive, a few species there rely on a different source for moisture. In the Namib, fog is way more common than rain. Some of it gets blown over on Atlantic winds; some of it radiates up from the ground. Altogether, there are usually between 60 and 200 foggy days in the desert each year.
The Namib grass Stipagrostis sabulicola exploits those foggy days. Airborne water droplets get caught on its leaves and tiny vertical grooves then redirect the liquid down to its roots. Small black insects in the Namib do something similar. On cool mornings, Namib beetles (Stenocara gracilipes) use their forewings to collect fog droplets and channel them into their mouths.
It's an ingenious hydration trick. So could mankind ever harvest fog? You bet. In fact, people all over the world are doing it right now.