Our atmosphere is a lot like an ocean. Stronger ocean currents, can mean you can get waves, and the atmosphere is similar.
There are different layers to our atmosphere. These layers can have different temperatures and even different wind speeds. This will help create different cloud formations and sometimes make them look wavy.
The white puffy clouds in this photo are cumulus clouds. They form around 3,300 feet above the ground. The clouds with ripples in them are cirrocumulus clouds. Sometimes cirrocumulus clouds are considered a “mackerel sky” since it looks like fishbones. These clouds form at 39,000 feet above the ground.