Meaning of supergranulation cell

su•per•gran•u•la'tion cell"

Pronunciation: (s"pur-gran"yu-lā'shun), [key]
— Astron. Astron.
  1. one of a number of large convection cells in the photosphere and chromosphere of the sun, each having a diameter of 10,000–20,000 mi. (16,000–32,000 km) and lasting longer than a day. Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.