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thumb|Supegranulation in the chromosphere of Sun. In solar physics and observation, supergranulation is a pattern of convection cells in the Sun's photosphere. The individual convection cells are typically referred to as supergranules. The pattern was discovered in the 1950s by A.B. Hart using Doppler velocity measurements showing horizontal flows on the photosphere (flow speed about 300 to 500 m/s, a tenth of that in the smaller granules). Later work (1960s) by Leighton, Noyes and Simon established a typical size of about 30000 km for supergranules with a lifetime of about 24 hours.