Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected. Mirrors exhibit specular reflection.
In acoustics, reflection causes echoes and is used in sonar. In geology, it is important in the study of seismic waves. Reflection is observed with surface waves in bodies of water. Reflection is observed with many types of electromagnetic wave, besides visible light. Reflection of VHF and higher frequencies is important for radio transmission and for radar. Even hard X-rays and gamma rays can be reflected at shallow angles with special "grazing" mirrors.
Green is the color of emeralds, jade, and growing grass. In the continuum of colors of visible light it is located between yellow and blue. Green is the color most commonly associated with nature and the environmental movement, Ireland, Islam, spring, hope and envy.
Postmodern architecture began as an international style the first examples of which are generally cited as being from the 1950s, but did not become a movement until the late 1970s and continues to influence present-day architecture. Postmodernity in architecture is said to be heralded by the return of "wit, ornament and reference" to architecture in response to the formalism of the International Style of modernism. As with many cultural movements, some of Postmodernism's most pronounced and visible ideas can be seen in architecture. The functional and formalized shapes and spaces of the modernist style are replaced by diverse aesthetics: styles collide, form is adopted for its own sake, and new ways of viewing familiar styles and space abound. Perhaps most obviously, architects rediscovered the expressive and symbolic value of architectural elements and forms that had evolved through centuries of building which had been abandoned by the modern style.
Influential early large-scale examples of postmodern architecture are Michael Graves' Portland Building in Portland, Oregon and Philip Johnson's Sony Building (originally AT&T Building) in New York City, which borrows elements and references from the past and reintroduces color and symbolism to architecture.
Postmodern architecture has also been described as neo-eclectic, where reference and ornament have returned to the facade, replacing the aggressively unornamented modern styles. This eclecticism is often combined with the use of non-orthogonal angles and unusual surfaces, most famously in the State Gallery of Stuttgart by James Stirling and the Piazza d'Italia by Charles Moore. The Scottish Parliament Building in Edinburgh has also been cited as being of postmodern vogue.
Varieties of the color green may differ in hue, chroma (also called saturation or intensity) or lightness (or value, tone, or brightness), or in two or three of these qualities. Variations in value are also called tints and shades, a tint being a green or other hue mixed with white, a shade being mixed with black. A large selection of these various colors is shown below.