Over San Antonio, Texas, US

The fibratus species of the high, ice-crystal clouds Cirrus and Cirrostratus (shown here) are when the clouds have been drawn out by the wind into long, fine filaments. These close strands of cloud appear rather like hair run through with a comb, and always form along the direction of the wind up at cloud level.

Full classification:

Other examples of fibratus:
Over Norwich, East Anglia, UK

Cirrus fibratus