You want to look your best before making a public appearance. These Altocumulus fluctus clouds, spotted by Patrick Dennis (Member 43,666) as they passed over the Rocky Mountains near Brighton, Colorado, US, have put in some curlers to get ready for their atmospheric promenade. Excellent curl definition!

Fluctus features like these form at the boundary between differing layers of air when there’s cloud in the lower layer and the flow of the winds above and below differ significantly. Typically, the airflow above is much faster than the airflow below. This difference in wind speeds, known as wind shear, can cause undulations to develop along the top surface of the cloud. And if conditions are just right, the tops of the undulations can be licked up and curled over by the faster winds above.

Fluctus features only last for a few minutes before dissipating in the turbulent airflow. With a fancy hairstyle like this, clouds need to get the timing just right if they’re to make a lasting impression.