Clouds. Always an interesting subject to study and photograph.
Cirrocumulus Cloud are often referred to as 'Herringbone' or 'Mackeral' clouds and occur at an altitude from 16,000 to 39,000. They are short lived and transitionary originally formed from Thunderstorm clouds 'Cumulonimbus anvil'.
NB. I had to look all this up as you may have guessed.
I can hear you yawning from here Trevor.{:))