1.This question is related to atmospheric turbulence. A. Explain the meaning of
ID: 154205 • Letter: 1
Question
1.This question is related to atmospheric turbulence.
A. Explain the meaning of the Law of Friction.
B. Explain how we can determine that the airflows are turbulent or laminar. Explain what the three regions of the energy spectra of atmospheric turbulence are. Explain why meteorologists apply the Reynolds decomposition and averaging of atmospheric variables.
C. Describe the conditions when atmospheric turbulence can be (i) homogeneous, (ii) stationary, and (iii) isotropic.
D. While studying air turbulence, explain when or where the ergodic condition is met.
E. Explain the meaning of the ‘frozen turbulence hypothesis’.
F. Provide examples of applications that require the use of turbulence intensity.
G. Suppose the following observations are made at a weather station, 10 m above the ground. Northwesterly wind blows steadily at 5 meters per second. An air eddy with a diameter of 100 m has a temperature of 20 oC on the most northwest region whereas the leading edge on the southeast region has a temperature of 10 oC. Assuming no vertical wind speed, use the ‘frozen turbulence hypothesis’ to estimate the local rate of change of air temperature as the air eddy is transported past the weather station.
Please answer the question completely, will give thumps up
Explanation / Answer
A) according to law of friction when an object is moving, the friction is proportional and perpendicular to the normal force. friction is independent of the area of contact so long as there is an area of contact . the coefficient of static friction is slightly greater than the coefficient of kinetic friction.
B) while laminar flow is "orderly" turbulent flow is "random" and "chaotic". it is also found that a flow in a pipe is laminar if the Reynolds number is less than 2100 and is turbulent if it is greater than 4000.
Three regions of energy spectrum of atmospheric turbulence are-
a) in regions over which the Spectre obey -5/3 power laws, the ratio of the lateral to the longitudinal spectra show fair agreement with the 4/3 ratio predicted by the kolmogorov hypothesis for the inertial subrange. The vertical longitudinal ratio has a similar tendency.
b) longitudinal expectra do not obey similarity theory in a number of ways. The wavelength do not scale with height, and there may be differences between sites when the spectra are plotted in similarity coordinates.
c) spectra over the sea seem to have relatively more energy at low frequency than those overland.
They apply the Reynold decomposition and averaging of atmospheric variables so that it can be used to separate the expectation value of a quality from its fluctuation in fluid dynamics and turbulence theory. it allows the simplification the Navier stoke equation by substituting in the sum of the study component and perturbation to the velocity profile and taking the mean value. The resulting equation contains and nonlinear term known as the Reynolds stresses which give rise to turbulence.
C) atmospheric turbulence can be homogeneous when there are no mean flow gradients.
Atmospheric turbulence can be isotropic when there is no mean shear, rotation or buoyancy effect in the flow as this can lead to anisotropy.
Atmospheric turbulence can be stationary when its quantity are relatively short when compared past few years.
D) an idealized atmospheric state where the ensemble average equals both the time and spatial averages.
Wild most turbulence theory are based on the ensemble average , most calculation of average in the real atmosphere averages over time of a fixed point , aur averages over a line on volume at an instant in time. By making the assumption ergodic, values measured in the real atmosphere can be utilised within the Reynolds averaged equation for turbulent flow.
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