Prognostic equation - in the context of physical (and especially geophysical) simulation, a prognostic equation predicts the value of variables for some time in the future on the basis of the values at the current or previous times.
For instance, the well-known
Navier-Stokes equations that describe the time evolution of a fluid are prognostic equations that predict the future distribution of velocities in that fluid on the basis of current fields such as the
pressure gradient
In atmospheric science, the pressure gradient (typically of Earth's atmosphere, air but more generally of any fluid) is a physical quantity that describes in which direction and at what rate the pressure increases the most rapidly around a particu ...
.
See also
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diagnostic equation In a physical (and especially geophysical) simulation context, a diagnostic equation (or diagnostic model) is an equation (or model) that links the values of these variables simultaneously, either because the equation (or model) is time-independent, ...
References
James R. Holton (2004) ''An Introduction to Dynamic Meteorology'', Academic Press, International Geophysics Series Volume 88, Fourth Edition, 535 p., , {{ISBN, 978-0-12-354015-7.
See also
http://glossary.ametsoc.org/wiki/Prognostic_equation
Atmospheric dynamics