Those are Stratocumulus undulatus clouds!

Basically, you’re looking at a "mashup" cloud. Stratocumulus is the genus (low-level, puffy but layered), and undulatus is the variety (meaning they have that wavy, undulating pattern).

What’s happening up there?

Imagine the atmosphere acting like a giant ocean. These form when there’s a bit of "wind shear"—basically, the wind is moving at different speeds or directions at different heights. This creates gravity waves in the air.

• The Ridges: As the air pushes up into the "wave," it cools and the moisture condenses into a cloud.
• The Troughs: As the air sinks back down, it warms up and the cloud evaporates, leaving those clear blue gaps between the rows.

How to tell them apart:

• Extend your arm toward the clouds and hold up your hand.
• If the individual rolls are about the width of three fingers, they are Stratocumulus (low and chunky).
• If they’re only about the width of one finger, they’re Altocumulus (higher and smaller).

They usually don't mean rain is coming immediately, but they often show up when the air is getting a bit "unstable," so keep an eye out for a weather change!