Interacting votices
The centre of smoke rings move the fastest and have the lowest pressure, (Bernoulli’s principle)
Because of the speed the centre is travelling at the sides curl back on themselves and are drawn into the centre from the back 1/2
Just published a short (hopefully broadly accessible) writeup on the ongoing outages at Facebook, Instagram & WhatsApp. Includes perspective, graphic from @dougmadory and Kentik. Will update to add more info soon. https://t.co/5C5fliBVqX