${\displaystyle \Delta t\leq \Delta x/c}$ 6(a)
In the context of climate modeling, ${\displaystyle c}$ refers not to the speed of light in a vacuum, but rather the maximum speed at which information can propagate through the medium being modeled Its value thus is different in atmospheric and oceanic models, but the condition holds in both cases: the timesteps must be short enough that even if it were to propagate at the maximum possible speed, information could not be communicated between one cell and another between one time step and the next.