you can easily earn this as your first achievement, along with your second as:
very early on you will have to complete quests given by the indicated sheep that involve clouds. all you have to do is use LB to split the clouds and then drag them back together to rejoin them. each newly split or joined cloud counts as a separate different cloud for this achievement. if you wait until your cloud is big enough to rain, you should be able to split it all down to many little clouds and repeatedly build it back up to knock both these out easily.