Pixar accompanies its CGI features with short films, and the shorts are usually thematically related in some way to the feature. Thus Up, which tells the story of a man who flies his house through the clouds by tying hundreds of helium balloons to it, is accompanied by Partly Cloudy, which tells what clouds get up to which we can't see. This turns out to be creating cloud babies, cloud puppies, cloud kittens, applying some cloud magic to turn them into living, breathing babies, puppies, kittens, and then turning them over to storks (Storks and clouds are, rather engagingly, partnered up) for delivery.
One cloud - rather more dirty than his white, fluffy companions - is tasked with creating the junior versions of the less engaging species, which he does very well. However, these biting, butting, stinging, stabbing creatures mean that his stork partner has the very worst job in the whole stork baby delivery fleet.
This wordless story is beautifully designed, brilliantly animated, beautifully communicated, full of slapstick humour and also genuine emotion and, like most of Pixar's shorts, it is very, very funny.
A class piece of work. I loved it.