From Pseudo Studios:
With iDaydream, you can create your own clouds in a virtual sky! Swipe your finger on the sky to create little puffs. Watch as the clouds you've just created float across the sky and shift shapes. You can control the wind direction, speed, and turbulence level to change the cloud effects.
Change the sky from daytime with white puffy clouds into a sunset filled with orange and purple clouds. Meanwhile, enjoy the occasional bird, plane and hot air balloon as they float by.