Johannesburg, or Joburg as it's called by the locals, is home to some of the most violent thunderstorms. They are beautiful and intense. After returning form London where I lived for half a year, the first thunderstorm completely freaked me out - I'd forgotten their immense force.
These storms are accompanied by some of the most lovely cloud formations and sunsets you're ever likely to see.
OK, enough superlatives.
Here's a shot from the roof of my flat the other night before a mild-in-comparison-of-what's-soon-to-come thunderstorm.
You can click on it to launch a 2560x1600 version to use a wallpaper if you wish.
And one with a September 2012 calendar for good measure: