page_title: Pattern
section_title: Chaos, turbulence, meanders and complexity
hierarchical_section_title: Pattern / Nature / Chaos, turbulence, meanders and complexity
caption_attribution_description: English: This Landsat 7 image of clouds off the Chilean coast near the Juan Fernandez Islands (also known as the Robinson Crusoe Islands) on September 15, 1999, shows a unique pattern called a "von Kármán vortex street." This pattern has long been studied in the laboratory, where the vortices are created by oil flowing past a cylindrical obstacle, making a string of vortices only several tens of centimeters long. Study of this classic "flow past a circular cylinder" has been very important in the understanding of laminar and turbulent fluid flow that controls a wide variety of phenomena, from the lift under an aircraft wing to Earth's weather. Français&#160;: Une allée de tourbillon de Karman dans les nuages provoquée par la rencontre entre du vent et une île des Juan Fernandez. Image prise par le satellite Landsat 7. Ce type de tourbillon est courament étudié au laboratoire, mais dans ce ces, ils ne font que quelques centimètres de long. עברית: תופעת הערבולים של פון קרמן כפי שנצפתה מעל האי Juan Fernández ליד צ'ילה. האי יוצר הפרעה לרוחות וכך נוצרת התופעה.
context_page_description: A pattern is a regularity in the world, in human-made design, or in abstract ideas. As such, the elements of a pattern repeat in a predictable manner. A geometric pattern is a kind of pattern formed of geometric shapes and typically repeated like a wallpaper design.
  Any of the senses may directly observe patterns. Conversely, abstract patterns in science, mathematics, or language may be observable only by analysis. Direct observation in practice means seeing visual patterns, which are widespread in nature and in art. Visual patterns in nature are often chaotic, never exactly repeating, and often involve fractals. Natural patterns include spirals, meanders, waves, foams, tilings, cracks, and those created by symmetries of rotation and reflection. Patterns have an underlying mathematical structure; indeed, mathematics can be seen as the search for regularities, and the output of any function is a mathematical pattern. Similarly in the sciences, theories explain and predict regularities in the world.
  In art and architecture, decorations or visual motifs may be combined and repeated to form patterns designed to have a chosen effect on the viewer.
context_section_description: Chaos theory predicts that while the laws of physics are deterministic, there are events and patterns in nature that never exactly repeat because extremely small differences in starting conditions can lead to widely differing outcomes. The patterns in nature tend to be static due to dissipation on the emergence process, but when there is interplay between injection of energy and dissipation there can arise a complex dynamic. Many natural patterns are shaped by this complexity, including vortex streets, other effects of turbulent flow such as meanders in rivers. or nonlinear interaction of the system
caption: Vortex street turbulence
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