Hendrik (Henk) Tennekes (born December 13, 1936, Kampen died July 3, 2021, Arnhem) was the director of research at the Royal Dutch Meteorological Institute (Koninklijk Nederlands Meteorologisch Instituut, or KNMI), and was a Professor of Aeronautical Engineering at Pennsylvania State University and Professor of Meteorology at the Vrije Universiteit Amsterdam (Free University (VU) in Amsterdam). He is known for his work in the fields of turbulence and multi-modal forecasting. He authored the textbooks The Simple Science of Flight: From Insects to Jumbo Jets and A First Course in Turbulence with John L. Lumley. The book "A First Course in Turbulence", is a classic that logs more than 2,000 citations on Google Scholar.