# Henry Charnock

Henry Charnock [1] (25 December 1920 – 28 November 1997), often credited as H. Charnock, was a British meteorologist.[2] He is well known for his work on surface roughness and wind stress over water surfaces. The now named "Charnok's relationship" describes the aerodynamic roughness length, ${\displaystyle z_{0}}$, over a water surface by:[3]

${\displaystyle z_{0}=Cu_{*}^{2}/g}$

where ${\displaystyle u_{*}}$ is the friction velocity and ${\displaystyle g}$ is the acceleration due to gravity (typically the Standard gravity). ${\displaystyle C}$ is Charnock's proportionality constant, shown to be 0.156.[4]

Charnock was President of the International Union of Geodesy and Geophysics (IUGG) from 1971 to 1975.

## References

1. ^ Cartwright, D. E. (1999). "Henry Charnock, C.B.E. 25 December 1920 -- 27 November 1997: Elected F.R.S. 1976". Biographical Memoirs of Fellows of the Royal Society. 45: 35. doi:10.1098/rsbm.1999.0004.
2. ^ "The Oxford Dictionary of National Biography". 2004. doi:10.1093/ref:odnb/68802.
3. ^ Stull, R. B. (1988). "An Introduction to Boundary Layer Meteorology". Kluwer Academic Publishers. ISBN 978-94-009-3027-8.
4. ^ Wu, J. (1969). "Wind stress and surface roughness at air-sea interface". Journal of Geophysical Research. 74 (2). pp. 444–455. doi:10.1029/JB074i002p00444.

## Bibliography

• 'CHARNOCK, Henry’, Who Was Who, A & C Black, 1920–2008; online edn, Oxford University Press, Dec 2007