JetStream - An Online School for Weather

On January 31, 2017, the Moderate Resolution Imaging Spectroradiometer (MODIS) flying aboard NASA's Terra satellite captured a stunning true-color image of cloud vortices induced by the island of Cheju Do, South Korea.

The swirling, paisley-like patterns are being formed by the turbulence created when southward-flowing air strikes the broad face of Mount Halla - a tall, broad-faced mountain that rises to 6,400 feet. The turbulent wind causes the clouds to flow in the large, spinning eddies seen in this image.

Known as von Karman vortex streets, such patterns occur in many situations, such as the vibration of car antenna at specific speeds, or wind impacting buildings. The size and shape of the eddies formed by the unsteady flow of a fluid around blunt bodies can be predicted with good accuracy via mathematical formulas, and this aspect of fluid dynamics is important in science, meteorology, and engineering. Only when clouds are present, however, is this beautiful pattern visible in the atmosphere. Enlarge image (~2 mb)

Welcome to JetStream, the National Weather Service Online Weather School. This site is designed to help educators, emergency managers, or anyone interested in learning about weather and weather safety.

The information contained in JetStream is arranged by subject; beginning with global and large scale weather patterns followed by lessons on air masses, wind patterns, cloud formations, thunderstorms, lightning, hail, damaging winds, tornados, tropical storms, cyclones and flooding. Interspersed in JetStream are "Learning Lessons" which can be used to enhance the educational experience.

You are free to use the materials in any manner you wish. We welcome your feedback on this project. Your input will greatly assist others in teaching the "hows" and "whys" of weather. Not sure where to begin? Click to see all topics in JetStream in the Topic Matrix.