They are! The description of the sketchbook I'm using says it's a fine tooth surface, which sounds a lot like your description of cellulose paper.
Media: Måla watercolor paints (Ikea)
Size: 8x10
Thanks for the feedback everyone! I'm glad you all like the clouds! That was totally intentional.
Did another today!
Reference image:
Painting (two steps):
I don't have white paint, and realized too late I painted over the sun area. I tried taking everyone's feedback into account!