What's causing these angry looking, low hanging clouds towering hundreds of metres above lake Malawi - on a seemingly otherwise bright, clear day?

What looks like dark cloud is in fact, recently hatched lake fly midges.

Yes, you're seeing that right - thats thousands upon thousands of midges clustered together in a mating frenzy.

In the rainy season, the midges break from the surface of the lack to mate. They then return to the surface to release their eggs, then die. And the cycle continues.

Take a look at the BBC's video showing you the process