# isotherm

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## isotherm,

line drawn on a map of a particular region of the earth's surface connecting points of equal temperature; each point reflects one temperature reading or an average of several readings over a period of time. The relative spacing of the isothermal lines indicates a temperature gradient, i.e., the amount of temperature change over a given distance.

## Isotherm

an isogram of the temperature of air, water, or soil. Most commonly drawn are isothermal maps showing mean monthly air temperature over a number of years, mean temperature for any period of time, or the temperature at a definite moment of time. To eliminate the influence of elevation when drawing isotherms, temperature values are sometimes reduced to sea level, assuming that air temperature drops an average of 0.6 °C for each 100 m of increase in elevation.

## Isotherm

a line on a phase diagram depicting a process occurring at constant temperature (an isothermic process). The equation of the isotherm of an ideal gas is pV = const, where p is the pressure and V is the volume of the gas. For a real gas the equation of an isotherm has a more complex character and becomes the equation for the isotherm of an ideal gas only at low pressures or high temperatures. On a pV diagram, at the point of intersection of the isotherm and the adiabatic curve the latter is steeper than the isotherm. The isotherms of ferromagnets in J, H, coordinates, where J is the magnetization and H is the magnetic field intensity, have a similar character.

## isotherm

[′ī·sə‚thərm]
(geophysics)
A line on a chart connecting all points of equal or constant temperature.
(thermodynamics)
A curve or formula showing the relationship between two variables, such as pressure and volume, when the temperature is held constant. Also known as isothermal.

## isotherm

The line on the weather chart joining places of equal temperature. These are normally drawn for even 5°C intervals. These lines are customarily indicated in red.

## isotherm

1. a line on a map linking places of equal temperature
2. Physics a curve on a graph that connects points of equal temperature
References in periodicals archive ?
When PHEG4000 crystallized isothermally at 36[degrees]C, the concentric spherulites could be observed (Figure 4(d)).
To understand the behavior of thermal decomposition of PFPE Ztetraol on a DLC substrate, PFPE Ztetraol is heated on a DLC substrate isothermally at different temperatures considering bond/break phenomenon.
We have introduced the paradigm of a signal amplification platform that isothermally and nonlinearly amplifies the recognition event between the aptamer and its substrate.
What the reader seems not to have realised is the change in buoyancy in the vessels when water compresses the air (isothermally), so the vessel on the sea bed always gains weight relative to the one on the surface and thus work has to be done in lifting it to the surface.
To survive the rough conditions through which many ag users put it, four of the five ductile iron castings were austempered, a process by which the ductile iron is isothermally heat treated and quenched in molten salt to produce ausferrite, a very strong, highly wear resistant casting structure.
Pristine PU samples (not subjected to UV) were annealed isothermally at various temperatures ([T.sub.a]) ranging from 0[degrees]C to 60[degrees]C for 8 h in a TA Instruments model Q1000[TM] differential scanning calorimeter (DSC), to determine how physical aging takes place at different temperatures.
(183 x 0.32 cm) SS column, was operated isothermally at 150[degrees]C with an He carrier at 25 mL/min, detector He at 30 mL/min, and an FID temperature of 250[degrees]C.
Then they were heated in a water bath ranging from 30 C to 90 C and held isothermally for 2 minutes, 5 minutes, 10 minutes or 15 minutes.
To prevent hot gases from condensing, all metal cells can be heated to 150 C, with an accuracy within 1[degrees], and are isothermally stabilized throughout the cell volume.
If, though, the chamber is not heated isothermally and the temperature is not constant throughout, the molecules may selectively resorb on colder spots.
Heat pipes can move heat at high rates over appreciable distances isothermally and without any external pumping.
In other words, a piston isothermally compresses a fixed supply of helium gas in one end of the cooler, then channels the gas to the other end of the cooler, where it expands.

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