These images are of some amazing storm clouds rolling over Lincoln, Nebraska this year.
These sorts of wave clouds are called "Undulatus Asperatus". Although they may look dark and forbidding, they tend to dissipate without actually forming a storm.
Undulatus Asperatus are rare, but storm chaser Alex Schueth managed to capture a brace of them on camera.
Watch the whole video here. Try not to get hypnotised.
