supergranulation
/ˌsuːpəˌɡranjʊˈleɪʃn/ /ˌsjuːpəˌɡranjʊˈleɪʃn/noun
1 Medicine = hypergranulation. rare.
2 Astronomy. A large convective cell in the surface layer of the sun, thousands of miles in diameter; a pattern or system of such cells.
Origin
Late 19th century. From super- + granulation.