•We
use the information of horizontal divergence to infer the vertical velocity.
However, for midlatitude weather, the horizontal divergence is due
primarily to the small departures of the wind from geostrophic balance. A
10% error in evaluating one of the wind components can easily cause the estimated
divergence to be in error by 100%.
•For
this reason, the continuity equation method is not recommended for estimating
the vertical motion field from observed horizontal winds.