Firstly, the water in the oceans and rivers evaporate, leaving the salt and muck behind and turning into water vapor.
Then after the water evaporates, it begins to condensate, it is when the small water pellets begin to start getting too heavy to be carried by the clouds.
Then when the condensation ends, the water is too heavy for the cloud, therefore begins precipitating, otherwise known as raining.
Then we have the nitrogen cycle, firstly, the atmospheric oxygen goes into the soil and nitrogen fixing bacteria converts nitrogen into ammonia, which is to be consumed by plants. And when animals eat the plant, they get nitrogen compounds in them.
Then other bacteria's turn those chemicals into nitrates and nitrites.
Then after, more bacteria turn the nitrates back into normal nitrogen, which gets returned to the atmosphere. (see next storyboard)