Complex sentence: His father was the Norwegian meteorologist Vilhelm Bjerknes (1862--1951), one of the pioneers of modern weather forecasting, and his maternal grandfather was Norwegian politician, Jacob Aall Bonnevie after whom he was named.
Split into simpler sentences: His father was the Norwegian meteorologist Vilhelm Bjerknes, one of the pioneers of modern weather forecasting. His maternal grandfather was Norwegian politician, Jacob Aall Bonnevie after whom he was named.