That is kind of wavy, which is how I imagine noctilucent clouds. Nacreous would have those pearlescent or opalescent colors, wouldn’t it? We see that all the time there are light clouds around the sun. They have bands of light green and light purple, especially bright near the sun but visible quite a distance away. This is in addition to sun dogs, which we also have nearly every day.
Yes, they’re pearlescent; and they’re in wave form; and they’re high stratospheric, rather than tropspheric.
Normal pearlescent or iridescent are much lower & more common.
Try these photo pages, and see some spectacular nacreous & a good explaination.
http://www.atoptics.co.uk/nacr1.htm
http://www.atoptics.co.uk/highsky/psc1.htm