The photo (right) shows a diffraction ring around the rising sun. A layer of thin clouds that caused it, and it dramatically disappeared when the sun rose high enough.
Lunar Diffraction Ring
This 1/10th second picture shows an overexposed full moon. The moon is in thin clouds which glow with a white disk surrounded by a red ring. A longer exposure would show more faint colors outside the red ring.
Diffraction from multiple slits, as described above, is similar to what occurs when waves are scattered from a periodic structure, such as atoms in a crystal or rulings on a diffraction grating.
Bragg diffraction is used in X-ray crystallography to deduce the structure of a crystal from the angles at which X-rays are diffracted from it.
The most common demonstration of Bragg diffraction is the spectrum of colors seen reflected from a compact disc: the closely-spaced tracks on the surface of the disc form a diffraction grating, and the individual wavelengths of white light are diffracted at different angles from it, in accordance with Bragg's law.
Diffraction also occurs when any group of waves of a finite size is propagating; for example, a narrow beam of light waves from a laser must, because of diffraction of the beam, eventually diverge into a wider beam at a sufficient distance from the laser.
Diffraction is one particular type of wave interference, caused by the partial obstruction or lateral restriction of a wave.
The most common demonstration of Bragg diffraction is the spectrum of colors seen reflected from a compact disc: the closely-spaced tracks on the surface of the disc form a diffraction grating, and the individual wavelengths of white light are diffracted at different angles from it, in accordance with Bragg's law.
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