A dopplergraph or dopplergram is a two-dimensional representation of the approaching and receding motions of an object or area.
The word "dopplergraph" is a combination of the words
doppler and
photograph
A photograph (also known as a photo, or more generically referred to as an ''image'' or ''picture'') is an image created by light falling on a photosensitivity, photosensitive surface, usually photographic film or an electronic image sensor. Th ...
. Dopplergraphs are two-dimensional records of variations in the
doppler shift
The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described t ...
in light intensity.
Dopplergraphs do not need to be a record of the shift of visible light, but of any radiated wave, which includes
electromagnetic waves
In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength, ran ...
and acoustic waves.
Because the doppler shift is caused by the velocity of the radiating source towards or away from the viewer, a dopplergraph is a picture of the velocities associated with the sources being viewed.
See also
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Spectrogram
A spectrogram is a visual representation of the spectrum of frequencies of a signal as it varies with time.
When applied to an audio signal, spectrograms are sometimes called sonographs, voiceprints, or voicegrams. When the data are represen ...
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Spectroheliograph
The spectroheliograph is an instrument used in astronomy which captures a photography, photographic image of the Sun at a single wavelength of light, a monochromatic image. The wavelength is usually chosen to coincide with a optical spectrum, spec ...
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Spectrohelioscope A spectrohelioscope is a type of solar telescope designed by George Ellery Hale in 1924 to allow the Sun to be viewed in a selected wavelength of light. The name comes from Latin- and Greek-based words: "Spectro," referring to the optical spectrum, ...
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Solar Dynamics Observatory
References
External links
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Doppler effects
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