Partly Cloudy is a Pixar CGI animated short film written and directed by Peter Sohn and produced by Kevin Reher. It was shown in theaters before Pixar’s feature film Up and is a special feature on its DVD and Blu-ray release. It was included in the Animation Show of Shows in 2009.
In a CGSociety article, Sohn says his idea for the film came from watching Dumbo as a child: in the movie, a stork delivers Dumbo, leading a young Sohn to wonder where the birds got their babies from. His conclusion was that the babies came from clouds, hence flying animals being needed to deliver them.