# isobar

## Definitions

• WordNet 3.6
• n isobar (meteorology)an isogram connecting points having equal barometric pressure at a given time
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Webster's Revised Unabridged Dictionary
• n Isobar (Phys. Geog) A line connecting or marking places upon the surface of the earth where height of the barometer reduced to sea level is the same either at a given time, or for a certain period (mean height), as for a year; an isopiestic line.
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Century Dictionary and Cyclopedia
• n isobar In physical geography, a line connecting places on the surface of the globe at which the barometric pressure is the same. For places not situated at the sea-level, a correction must be applied to each barometric observation corresponding to the elevations of the stations, before the isobar connecting such stations can be drawn. Isobars may be purely imaginary lines; but generally, that the distribution of the pressure may be seen at a glance, they are drawn upon some kind of map or chart of the regions covered by the observations. Isobars may be such as indicate the distribution of barometric pressure at a certain specified day and hour, or they may give the mean pressure for any period of time, as for the entire year or for the summer or winter months. Also called isobarometric line.
• n isobar In thermodynamics, a line or curve determined by the equation of state (pv = RT) of a system when p has any constant value; a line of equal pressures.
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Chambers's Twentieth Century Dictionary
• n Isobar ī′so-bär an imaginary line connecting places on the earth where the mean height of the barometer at sea-level is the same
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## Etymology

Webster's Revised Unabridged Dictionary
Iso-, + Gr. weight
Chambers's Twentieth Century Dictionary
Gr. isos, equal, baros, weight.

## Usage

### In literature:

Isobaric and Isothermal Lines.
"General Science" by Bertha M. Clark
One of the maps shows the actual isobars as they were recorded by the Weather Bureau.
"The Right Time" by Walter Bupp
The isobaric and wind charts show that on the whole the winds blow out from the inner polar basin, especially in winter and spring.
"Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 5" by Various
A cyclone with crowded isobars always has strong winds; when the isobars are widely spaced the winds are gentle.
"The Mentor: The Weather" by Charles Fitzhugh Talman
In most cases the 29.80-inch isobar furnishes a good limit, out to which the isobars may be traced.
"Practical Exercises in Elementary Meteorology" by Robert DeCourcy Ward
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### In news:

Chicago Mayor Rahm Emanuel says Roundarch Isobar , a digital design firm located downtown, will double its staff, adding 150 to 200 jobs over the next five years.
Mark Cridge, the global managing director of Aegis Media's Isobar network and founder of Glue, has decided not to return to the business following a six-month sabbatical.
Founder Mark Cridge to exit Glue and Aegis Isobar network.
Mark Cridge walks away from Glue Isobar after 13 years.
Both will work across Isobar 's four divisions in the UK: Glue Isobar , Isobar Mobile, Isobar Social and Superglue.
McDonald will lead Isobar 's planning offering, working closely with Tim Dunn, the head of strategy at Isobar Mobile.
Bailie will focus on driving new revenue streams for the Isobar UK business.
Martin Bailie, executive planning director, Glue Isobar .
When you see lots of isobars over an area, most likely that area is experiencing lots of wind (due to the difference in air pressure).
An isobar is a line of constant pressure.
Raising the isobar on forecasts.
Chicago Mayor Rahm Emanuel says Roundarch Isobar, a digital design firm located downtown, will double its staff, adding 150 to 200 jobs over the next five years.
Now, Malibu and its digital creative agency Isobar are extending that summer feeling all year round with a new Facebook game application.
Mark Cridge, the global managing director of Aegis Media's Isobar network and founder of Glue , has decided not to return to the business following a six-month sabbatical.
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### In science:

Because the star is rotating, the equilibrium isobars are not spherical, but nearly (the stellar radius is larger at the equator than the pole by ≈ R2Ω2/g ≈ 100 m for typical parameters).
Rotational Evolution During Type I X-Ray Bursts
Such ﬂuctuations are quasi-adiabatic rather than quasi-isobaric in the large-η limit, and trigger the wave mode of TI, rather than the condensation mode, being stable to ﬁrst order.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
As mentioned in the Introduction, in this paper we are concerned with cooling functions which imply instability only for the isobaric mode.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
Therefore, isobaric evolution cannot occur at scales larger than a few parsecs.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
In this limit, the velocity perturbations are unstable when the isobaric condition is satisﬁed, because they behave as a condensation mode (see, e.g., Shu 1992; Paper III).
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
As expected, although the pressure is not perfectly constant (see Fig. 2b), the evolution can be considered as quasi-isobaric, as can be seen in Figure 4.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
This value of η explains the approximately isobaric evolution of the ﬂow across this region, which is characterized by relatively low densities (ρ . 0.7 cm−3 ).
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
The ﬁnal slow-growth state of this large-scale perturbation is actually very similar to that of DEN3, after the shock has established a quasi-isobaric regime.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
Consequently, the condensations behave essentially as entropy perturbations, and evolve approximately isobarically (cf. §3).
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
These studies are related to the issues we discuss in §§3.3 and 4.3, although in our case the medium is already isobarically unstable from the start.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
Thus, in a sense, the velocity ﬂuctuations even in our simple 1D case have the effect of counteracting the development of the isobaric mode of TI analogous to that of the dynamical instabilities discussed by other authors.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
Moreover, the accreting gas is not in thermal equilibrium, but in a nearly isobaric regime, in which the (small) pressure ﬂuctuations have the same sign as those of the density, and therefore the medium has no strong tendency to fragment any further.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
We have found that the evolution for initial Gaussian perturbations of FWHM smaller than ∼ 15 pc is approximately isobaric.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
The unperturbed density ρ0 , and the cloud density resulting from isobaric evolution ρisob , are shown.
The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
We ﬁt according to Eq. (4) the data in the T range 247272 K at atmospheric pressure, where log10 τ is linear vs. (T Sexc )−1 ), and all the isobaric dielectric data at higher pressures.
Can experiments select the configurational component of excess entropy?
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