Grumpy Cumulonimbus

These Cumulonimbus clouds are constantly grumpy because of the horrible cycle they have to go through.
The Cumulonimbus cloud is born with constant constipation and thus causes great discomfort. It has to remove it's excrement in order to reduce the pain of consipation. However, the shape of their excrement is very jagged and gives off an electrical discharge which causes even more pain when released.
Their urine is slightly acidic due to pollution from below so that also causes the Cumulonimbus pain. Also when urinating the urine usually lands on the top of another Cumulonimbus casing pain not only from the bottom but from the top.
When they fart the sound is so loud that it gives them a headache, because the fart can travel for miles it affects other Cumulonimbus clouds.
Once the Cumulonimbus has finished it's business it simply dissapears into nothing but it's own urine which will form another Cumulonimbus at the right temperature and so the horrible cycle continues.

Excrement/poop is known as Lightning to humans.
Urine is known as Rain to humans.
Fart is known as Thunder to humans.