Features that form the chromospheric network on the Sun, visible in Hα and calcium K-line spectrograms. They cover the entire Sun, quiet and active regions alike. Coarse mottles are bright, up to about 20 000 km across, and often elongated. They merge to form plages. Fine mottles are narrow (700 km wide, up to 7000 km long), dark or bright, and are probably spicules seen against the disk. Fine mottles form clusters with their bases rooted in the coarse mottles. All coincide with regions of strong magnetic field on the photosphere.
Subjects: Astronomy and Astrophysics.