Nature is not particularly generous when it comes to producing individuals with both great intellectual and humanitarian qualities. Douglas K. Lilly, or simply Doug, is a rare example of a person who essentially combines these two virtues.

As will become apparent from the scientific articles collected in this volume, Doug has earned an outstanding reputation worldwide for the very high caliber of his contributions to the fields of meteorology and geophysical fluid dynamics. Less evident, but not less striking, is the dignity of his character, his modesty, and his dedication to truth. Of pioneering stock, Doug still embodies the best of the pioneering spirit: vision, individualism, fearlessness, and obliviousness of authority. His fairness of judgements co-existing with his friendliness to colleagues and dedication to students has become almost legendary. Doug has made many friends throughout the years at the various places where he has worked, and is respected and admired by students and prominent scientists alike.

This collective volume, dedicated to Doug on the occasion of his 75th birthday, begins by focusing on Doug the man. His biography, written by K. Kanak, a recent Ph.D. student of Doug, traces his scientific evolution by incorporating recollections of several people, who worked with Doug, beginning with those of J. Smagorinsky, Doug's post-doc advisor. Doug's fundamental work on the numerical simulation of turbulence dates back to his interactions with Smagorinsky and K. Bryan while at the Geophysical Fluid Dynamics Laboratory (GFDL) in the late 1950s and early 1960s. In the latter part of the 1960s, Doug went to the National Center for Atmospheric Research (NCAR), where he continued to develop his interests in numerical simulation in collaboration with J. Deardorff.