Glossary of Scientific Terms

New terms are being added all the time!

internal gravity waves

Internal gravity waves are like surface waves on the ocean, they both propagate under the restoring force of gravity. The restoring force is felt when there is a vertical variation in density such as the density difference between water and air. When the density difference is very large (at the interface between two fluids, like water and air) waves are trapped at the interface and you have surface waves. When the density varies gradually as in a stratified fluid internal gravity waves may exist. Such waves may move vertically upward as well as horizontally.

In the atmosphere, the effect of internal gravity waves can be seen on partly cloudy days. The rise and fall of the waves at just the right altitude can make wave condense and evaporate, respectively, and this leads to a banded cloud pattern.

stratified fluid

In a stratified fluid the density varies with depth. Such circumstances occur naturally, for example, due to variations in temperature in the atmosphere, and due to temperature and salinity variations in the ocean.

Fluid Dynamics Laboratory home page
Bruce R. Sutherland, Jan 96,