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below the inversion, since the normal convective the set of all semantically well-formed mappings
process which drives the warmer and lighter air operating on K and ;(K) is the set of defined
at ground-level to higher altitudes is interrupted semantics for the members of K.
as the rising air parcels encounter the warmer air Comment: This notion of term semantics
above. Temperature inversions near the surface extends in the domain direction the notions of
are particularly effective in trapping ground-level semantics of programs, and is consistent with it.
emissions. See semantics and semiote.

temperature jump A relaxation technique
term, T Energy divided by the product of
in which the temperature of a chemical system
the Planck constant and the speed of light, when
is suddenly raised. The system then relaxes to
of wave number dimension, or energy divided by
a new state of equilibrium, and analysis of the
the Planck constant, when of frequency dimen-
relaxation processes provides rate constants.
sion.
temperature lapse rate (in atmospheric chem-
istry) The rate of change of temperature terminal nodes The first and last nodes in
with altitude (dT /dz). The rate of tempera- the sequence of nodes and edges forming a path.
ture decrease with increase in altitude which is If the path is a connected tree, the last nodes are
expected to occur in an unperturbed dry air mass the leaves of the tree (letting the root of the tree
−1
is 9.8 × 10 C min . This is called the dry be the first node of the sequence). See also path
3 ◦
adiabatic lapse rate. The lapse rate is taken and sequence.
as positive when temperature decreases with
increasing height. For air saturated with H O
2
the lapse rate is less because of the release of test sample The sample, prepared from the
laboratory sample, from which test portions are
the latent heat of water as it condenses. The
removed for testing or for analysis.
average tropospheric lapse rate is about 6.5 ×
−1
10 C min . The lapse rate has a negative value
3◦
within an inversion layer. theorem of the alternative Any of several
theorems that establish that two systems are alter-
tensor See contravariant tensor. natives. See, for example, Fredholm alternative.
term (1) A variable, constant, or complex
thermal conductance, G G G Heat flow rate
expression of the form f(σ ,σ ,...,σ ) where divided by the temperature difference.
2
n
1
there exists at least one σ (that is, the arity of f is
i
always positive). If f is a relation (or predicate)
symbol, then f(σ ,σ ,...,σ ) is an atomic for- thermal conductivity, λ λ λ Tensor quantity
1 2 n
mula. relating the heat flux, J to the temperature gra-
q
Comment: Note that this definition is recur- dient, J =−λ grad T .
q
sive(atermiseitheratermorafunctionofterms),
and that it includes both variable and constant (or
thermal resistance, R R R Reciprocal of the
ground) terms. It is taken to be synonymous with
thermal conductance.
token.
(2) (in x-ray spectroscopy) A set of levels
which have the same electron configuration and thermodilatometry A technique in which a
the same value of the quantum numbers for total dimension of a substance under negligible load is
spin S and total orbital angular momentum, L. measured as a function of temperature while the
substance is subjected to a controlled tempera-
term semantics If for each σ ∈ K there is ture program.
j
at least one semantic mapping ω that is semantic- Linear thermodilatometry and volume
ally well formed, then we say the term semantics thermodilatometry are distinguished on the basis
of ;: K −→ ;(K) are well-formed, where ; is of the dimensions measured.

© 2003 by CRC Press LLC
© 2003 by CRC Press LLC