Measure Of Kinetic Energy Research Articles

Testing the phonon spectrum of metallic chromium with the nuclear-resonance photon scattering technique.

The nuclear-resonance photon-scattering cross section ${\mathrm{\ensuremath{\sigma}}}_{\mathit{s}}$ from $^{50}\mathrm{Cr}$ in a metallic form was studied as a function of temperature in the range 15--300 K. The value of ${\mathrm{\ensuremath{\sigma}}}_{\mathit{s}}$ was used for deducing the effective temperature ${\mathit{T}}_{\mathit{e}}$ which is related to a weighted average of the phonon spectrum of metallic Cr. This ${\mathit{T}}_{\mathit{e}}$ is also a measure of the total zero-point kinetic energy of the lattice and was used to define another Debye temperature ${\mathit{FTHETA}}_{0}$; its value for metallic Cr was measured and found to be ${\mathit{FTHETA}}_{0}$=510\ifmmode\pm\else\textpm\fi{}20 K. This value is higher by about 10% than that obtained from the known phonon spectrum deduced by inelastic neutron scattering. A similar deviation occurs in other elements. The reason for this deviation of the values of ${\mathit{T}}_{\mathit{e}}$ and hence of ${\mathit{FTHETA}}_{0}$ obtained by the nuclear-resonance photon-scattering technique and by inelastic neutron scattering is discussed.

The Structure of Mean Circulations

A discussion of the best mode of expressing the facts of the mean westerly flow in temperate latitudes parametrically leads to the result that over North America the shape of the vertical geostrophic westerly wind profile is nearly invariant with respect to time and place. The vertical wind profile can be expressed in terms either of the change pressure-gradient with height, or of contour-height gradient with pressure-level. In either case the profile shape is characteristic, and varies little with season, longitude or latitude over North America. The intensity of the mean circulation varies rythmically with season, but that for any one month may vary markedly from year to year. The profile shape for an oceanic region differs from that of a land region such as eastern North America in exibiting a lower ratio of high-level to surface wind, and in being much more variable from month to month. It is shown that the pressure-difference at 7 km between two latitudes, or the difference in mean height of the 200 mb surface gives a measure of the total geostrophic momentum between those latitudes. The square of these quantities also gives a measure of the total kinetic energy of the westerlies between these two latitudes. DOI: 10.1111/j.2153-3490.1951.tb00808.x

The Structure of Mean Circulations

A discussion of the best mode of expressing the facts of the mean westerly flow in temperate latitudes parametrically leads to the result that over North America the shape of the vertical geostrophic westerly wind profile is nearly invariant with respect to time and place. The vertical wind profile can be expressed in terms either of the change pressure-gradient with height, or of contour-height gradient with pressure-level. In either case the profile shape is characteristic, and varies little with season, longitude or latitude over North America.
 The intensity of the mean circulation varies rythmically with season, but that for any one month may vary markedly from year to year.
 The profile shape for an oceanic region differs from that of a land region such as eastern North America in exibiting a lower ratio of high-level to surface wind, and in being much more variable from month to month.
 It is shown that the pressure-difference at 7 km between two latitudes, or the difference in mean height of the 200 mb surface gives a measure of the total geostrophic momentum between those latitudes. The square of these quantities also gives a measure of the total kinetic energy of the westerlies between these two latitudes.