Main Page | See live article | Alphabetical index Transverse waves are those in which the particle motion is perpendicular to the direction of propagation. They travel slower than longitudinal waves (where the particle motion is in the direction of travel), and propagate only in solids, not in liquids or gases. In seismology transverse waves are called S (for “secondary”) waves as they arrive later than the P (“primary”) waves from an earthquake. The absence of transverse waves traveling through the earth’s core shows that it is liquid. In mathematics, transverse waves are associated with the “curl” operator and are governed by a vector wave equation, in contrast to longitudinal waves, which are associated with the “div” operator and are governed by a scalar wave equation. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.