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[′presh·ər ‚grād·ē·ənt]
(fluid mechanics)
The rate of decrease (that is, the gradient) of pressure in space at a fixed time; sometimes loosely used to denote simply the magnitude of the gradient of the pressure field. Also known as barometric gradient.
(meteorology)
The change in atmospheric pressure per unit horizontal distance, usually measured along a line perpendicular to the isobars.

the change in atmospheric pressure per unit of distance along a normal toward an equal pressure surface (isobaric front) in the direction of a decrease in pressure.

Horizontal pressure gradients are commonly used in meteorology—that is, horizontal components of pressure gradients established at sea level or at another level. In this case, the isobaric normal toward an isobar is taken at a given level. Normally a horizontal pressure gradient is 1–3 millibars per 100 km, but in tropical cyclones the gradient sometimes reaches tens of millibars per 100 km (1 millibar = 100 newtons per sq m). The concept of a barometric grade is often used instead of the vertical pressure gradient.

The change in pressure with horizontal distance at a fixed time. The higher the pressure gradient, the faster is the fluid flow.
References in periodicals archive ?
where s is volume percentage of mobile fluid; [s.sub.0] is the calibration value of volume percentage of mobile fluid; r is throat radius; [r.sub.0] is the calibration value of throat radius; A is the start-up pressure gradient; [[lambda].sub.0] is the calibration value of start-up pressure gradient; m is clay mineral content; [m.sub.0] is the calibration value of clay mineral content; D is the comprehensive evaluation parameter for advantageous reservoirs.
In Figure 1, the slope at any point stands for the permeability at the correlated pressure gradient. In this way, the relationship between permeability and pressure gradient can be obtained, as shown in Figure 2.
Due to a smaller exponent set for the speed in the power-law calculations, the impact of this pressure gradient decreases for increasing speeds.
If wood is immersed in a dye solution for extended periods of time during the dyeing process, pressure gradients cannot be created within the wood.
In Figure 4, [bar.w] is plotted together with the pressure gradient [partial derivative]p/[partial derivative]z.
High pressure gradient has been observed at annular flow pattern than in any other flow patterns.
We found that replacing a stenotic aortic valve with a Hancock II porcine bioprosthesis resulted in low mean pressure gradients during both rest and peak exercise, above average exercise capacity at six months postoperatively, and significant improvement in overall quality of life.
Pressure gradient, not exposure duration, determines the extent of epithelial cell damage in a model of pulmonary airway reopening.
As leaves are transpiring rapidly during a warm or hot day, the pressure gradient points toward the leaves.
Two flow problems are considered: (i) Flow in an oscillating rectangular duct and (ii) Flow in a duct induced by an oscillating pressure gradient.
Tenders are invited for acquisition of an ion chromatography system equipped with a high pressure gradient, electrochemical detector, automatic dilution and tangential ultrafiltration of samples, for laa madrid.

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