That's experts on real clouds in the real sky, not the virtual cloud, although it's not impossible that an expert in one kind of cloud could be an expert in the other.
I took a number of photos of these clouds near sunset on 21 December 2015 in Johannesburg and would appreciate your feedback on what kind of clouds these are. Not only am I curious about what these clouds are, I find them extremely beautiful, and the setting sunlight on them was memorable and mesmerising.
Back to identifying them!
I think they might be partially-formed mammatus clouds. We sometimes see mammatus clouds in Johannesburg before thunderstorms - and our thunderstorms are typically ferocious. Here's a dramatic example of well-formed mammatus clouds from one of my favourite feeds, www.earthsky.org:
And for those who are wondering where the name mammatus comes from, yes, it is what you're thinking.
Here's another example from the Weather Channel:
Was there a thunderstorm that day?
I looked for weather data for that day; I remember that week before Christmas was brutally hot, but can't remember if we actually had a thunderstorm. Without a South African Weather Service account, the best I can do is access a weekly rainfall picture for the country:
Some more shots to help with identification - and just because those clouds are beautiful
Here are some more shots of the clouds I observed on 21 December 2015, if the different angles will help you with identification:
Look forward to your Steemian knowledge and insights!