Nigel Oscar Weiss FRS[4] (16 December 1936 – 24 June 2020)[2][3] was an astronomer and mathematician, and leader in the field of astrophysical and geophysical fluid dynamics.

[5] In 1966 he was the first to demonstrate and describe the process of 'flux expulsion' by which a conducting fluid undergoing rotating motion acts to expel the magnetic flux from the region of motion, a process now known to occur in the photosphere of the Sun and other stars.

[2] His nomination reads Professor Weiss is distinguished for his work in the theory of convection, for developing appropriate numerical techniques, and for pioneering their use in precise numerical experiments to gain a qualitative and comprehensive understanding of the behaviour of complicated nonlinear systems.

Among many notable achievements in this field, he has been instrumental in the identification of a period-doubling route to chaos in a system of partial differential equations describing doubly-diffusive convection.

He has made wide-ranging studies of the magneto-convective processes occurring in the Sun and similar stars.