Warm advection beneath an upper level ridge causes it to build (increase in amplitude), while cold advection beneath an upper level trough will contribute to its deepening. The animation below highlights the amplification of ridge/trough system at 250 mb in response to intense thermal advection at 850 mb. The total time elapsed in the animation is 48 hours.

Observe how the ridge over the east gradually builds (raises northward) while the trough over the northern plains gradually deepens (sinks southward). While the entire ridge/trough system propagates eastward. Such amplification of upper level waves can increase the intensity of a cyclone at the surface.

ridges

Terms for using data resources. CD-ROM available. Credits and Acknowledgments for WW2010. Department of Atmospheric Sciences (DAS) at the University of Illinois at Urbana-Champaign.

rising motion