Explorations: Atmospheric Gravity Waves
Atmospheric gravity waves are not to be confused with gravitational waves, which are a fluctuation in the curvature of spacetime, which propagates as a wave traveling outward from a moving object or system of objects. The Wikipedia gravitational wave entry has more on these.
The atmospheric gravity waves shown in the graphic on page 219 of The AMS Weather Book are the same kind of waves as the ocean waves described on pages 65 and 66 of the book. Waves of this kind need a disturbing force, such as wind for water waves and wind being forced up by a mountain, as shown in the book’s atmospheric waves graphic, or the movements of fronts, plus a restoring force. The restoring forces for atmospheric gravity waves are gravity and buoyancy.
NASA Earth Observatory’s Atmospheric Gravity Waves over Arabian Sea Web page illustrates and briefly explains one kind of gravity wave.
An animated satellite image of a gravity wave train of clouds (an undular bore) was captured on a sequence of GOES-12 visible images as it propagated southward across the northwestern Gulf of Mexico on 15 March 2008 (from the CIMSS Satellite Blog).
Multi-Community Environmental Storm Observatory’s “Gravity Waves: What’s the Attraction? (PDF file)” is intended for forecasters, but it’s not overly technical and should be understood by readers of The AMS Weather Book.
On May 27, 1997, supercell thunderstorms spawned numerous tornadoes, dropped large hail, and produced damaging surface winds in the Austin, Texas, area. Three strong tornadoes, including one F-5, killed 28 people and caused several million dollars in damage. A gravity wave helped trigger the storms.
NOAA, A Meteorological and Radar Analysis of the Central Texas Tornado Outbreak on May 27, 1997 (technical memorandum, NWS SR-198, July 1998) describes the meteorology of the event, including the role of the gravity wave. An NWS Storm Prediction Center article offers another look at the meteorology of the May 27, 1997, outbreak. While these two documents are intended for meteorologists, readers of The AMS Weather Book who are willing to look up unfamiliar terms should be able to grasp their main points. Reading these would be good mental exercise for readers who are thinking of studying meteorology.