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Bernoulli's principle states that an increase in the speed of a parcel of fluid occurs simultaneously with a decrease in either the pressure or the height above a datum. [1]: Ch.3 [ 2 ] : 156–164, § 3.5 The principle is named after the Swiss mathematician and physicist Daniel Bernoulli , who published it in his book Hydrodynamica in 1738. [ 3 ]
The increase of temperature with altitude is a result of the ... above which the temperature decreases with height. ... reached with a peak velocity of 1,321 km/h ...
Potential temperature is a useful measure of the static stability of the unsaturated atmosphere. Under normal, stably stratified conditions, the potential temperature increases with height, [3] > and vertical motions are suppressed. If the potential temperature decreases with height, [3] < the atmosphere is unstable to vertical motions, and ...
For an ideal gas (see gas laws), the stability criterion for an air column is that potential temperature increases monotonically with height. To understand this, consider dry convection in the atmosphere, where the vertical variation in pressure is substantial and adiabatic temperature change is important: As a parcel of air moves upward, the ...
From the ground upwards through the troposphere temperature decreases with height; from the tropopause upwards through the stratosphere temperature increases with height. Such variations are examples of temperature gradients. A horizontal temperature gradient may occur, and hence air density variations, where air velocity changes. An example ...
When a parcel of air descends, the pressure on the parcel increases. Because of this increase in pressure, the parcel's volume decreases and its temperature increases as work is done on the parcel of air, thus increasing its internal energy, which manifests itself by a rise in the temperature of that mass of air.
Thus, indirectly, thermal velocity is a measure of temperature. Technically speaking, it is a measure of the width of the peak in the Maxwell–Boltzmann particle velocity distribution . Note that in the strictest sense thermal velocity is not a velocity , since velocity usually describes a vector rather than simply a scalar speed .
When stated in terms of temperature differences, Newton's law (with several further simplifying assumptions, such as a low Biot number and a temperature-independent heat capacity) results in a simple differential equation expressing temperature-difference as a function of time. The solution to that equation describes an exponential decrease of ...