"It is difficult to gauge the height of these clouds from this photo, but they look about 5000-8000ft above ground level. This would make them stratocumulus. If I am mistaken and they are middle-level clouds they would be alto-cumulus. In either case though, this cloud formation is often fairly shallow and spread over a large area," says Warren Tennant of the SA Weather Service in Pretoria when asked about this interesting cloud formation that was seen over the central Greater Kruger area recently.
He says it will typically be found below an inversion or stable layer in the atmosphere. This is common along the coast and in the lowveld, where warmer air from the interior overlies the cooler coastal air. "However, what is interesting about this picture is the apparent straight line along the edge of the cloud bank. We seldom see such a long straight line like this but it would be caused by a boundary between moist air and dry air as the air from the coast meets the dry continental air or even tropical moist air to the north and dry air to the south."