Nebulous Nomenclature
An excercise in recreational etymology
A good dictionary contains many words with beginning with nephel- or
nepho- which have to do with clouds. Both prefixes are Greek
derivatives of the Indo-European root nebh- (``cloud''). Other
offshoots lead to the Latin words nebula
and nimbus
and the Old Norse Niflheim.
Meteorological Terms
A number of words with the Greek root have been used in the study of
terrestrial weather:
- nephanalysis - n (1945) : 1. the analysis of the clouds
and related phenomena over a large area of the earth on a chart used especially
in weather forecasting; 2. the chart itself
- nephelognosy - n : scientific observation of clouds
- nephelometer - n (1875) : 1. an instrument for measuring
the extent or degree of cloudiness; 2. an instrument for determining the
concentration or particle size of suspensions by means of transmitted or
reflected light ; also nephelometry (n), nephelometric
(adj)
- nepheloscope (also nephelescope) - n : an
instrument for demonstrating cloud formation in the laboratory by expansion of
moist air
- nephogram - n : a photograph of clouds
- nephograph - n : an instrument for photographing clouds
- nephology - n : the science of clouds; a branch of
meteorology dealing with clouds ; also nephological (adj)
- nephometer - n (1910) : nephelometer
- nephoscope - n (1881) : an instrument for observing the
direction and velocity of clouds
These are taken from multiple sources; dates of origin are shown where
available.
Interstellar Extrapolations
A few years ago, Linsky
& Wood (1996 ApJ 463, 254) invented a new word, astronephography,
to describe the 3-D mapping of interstellar clouds, in direct analogy to geography's
mapping of the Earth. Here astroneph- translates literally as
``star-cloud'', which should be interpreted as clouds among the stars,
not as clouds of stars (though, before their nature was understood,
galaxies outside the Milky Way used to be called nebulae along with
true interstellar clouds of gas and dust).
While the new word rolls off the tongue nicely, it doesn't mesh with the
meteorological labels. Linsky & Wood's work did not involve the direct
imaging which nephography implies, but rather some clever model
construction based upon careful studies of stellar spectra. Agreement with the
older nomenclature is hardly mandatory of course, but here's what an
alternative scheme which strives to remain consistent might look like:
- astronephology - n : the science of star-clouds; includes
the following
- astronephelognosy - n : observation of star-clouds;
includes
- astronephography - n : imaging of star-clouds; the subset
of this involving the precision measurement of star-cloud extent, brightness
and transparency is astronephelometry
- astronephoscopy - n : measuring positions and velocities
of star-clouds (can be loosely interpreted as spectroscopy, which would give
velocities via doppler shifts, or one could make an uglier word, like
astronephospectroscopy, to be more precise)
- astronephanalysis - n : analysis of star-clouds
(strictly, over a large area, perhaps using a survey like the CGPS); a subset concerned with
mapping 3-D cloud distributions using various observations might be called
astronephocartography
- astronephophysics - n : physical theory of star clouds
(no meteorological root for this one, but a pure theory category is needed to
fill out the tree)
Of course, since nebula in modern usage refers to star-clouds rather
than terrestrial clouds, the astro- prefix may be redundant in all of
these. But then what fun is that?
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