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Robert G. Fleagle

Abstract

The equation of motion is derived for a compressible fluid cooling at the bottom by contact with a radiating surface of uniform slope and large extent. During the early stages the drainage velocity is found to vary periodically about an equilibrium value. The equilibrium value is proportional to the net outgoing radiation from the ground, and is inversely proportional to the height to which cooling extends and to the slope of the ground. The rate at which equilibrium is attained depends upon the assumed form of the frictional force. In the absence of detailed observations of drainage velocities, it is concluded tentatively that the assumption of a frictional force which is proportional to the square of the velocity gives fairly realistic results.

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Robert G. Fleagle

Abstract

It is shown that the lowest temperature to which a radiating surface may fall depends upon the thickness of the ground surface layer which undergoes temperature change, the conductivity of the layer, and the presence of obstructions above the plane of the horizon. Integration of the heat conduction equation results in a solution which differs markedly from that given by Brunt (1932, 1941) for constant radiation. Groen's (1947) solution is shown to represent the special case of a layer of great thickness. Computations for a valley containing a frozen river, light and compact snow, and bare granite indicate that local temperature differences of 1OC or more may occur when radiation is of primary importance.

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Robert G. Fleagle

Abstract

The local twelve-hour change of temperature lapse rate from 5,000 to 10,000 feet is computed in 50 cases as a function of horizontal velocity divergence and vertical variation of horizontal temperature advection, and the result compared with the observed change of lapse rate. The divergence is measured from charts of horizontal velocity components; the vertical variation of horizontal temperature advection is measured by the rate of flow across the isotherms at two different levels and, as an alternate method, by the hodograph. The standard errors of estimate for these two methods are, respectively, 2.2 and 4.4 C km−1. The reliability of the measurements of divergence is studied by comparing the measured values with values computed from the difference between observed change of lapse rate and vertical variation of advection. The correlation coefficient relating these two methods is + 0.60 when advection is measured on constant level charts and + 0.40 when advection is measured by the hodograph.

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Robert G. Fleagle

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Robert G. Fleagle

Abstract

The fields of temperature, pressure, and three-dimensional motion are shown on horizontal charts and vertical cross sections for a period of anticyclogenesis above a polar anticyclone and for periods of cyclogenesis in Colorado and on the east coast of the United States. Prominent features of the charts are indicated, and certain outstanding relationships connecting temperature advection, vertical component of velocity, and local pressure change are discussed.

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Robert G. Fleagle

Abstract

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Robert G. Fleagle

Abstract

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Robert G. Fleagle

Abstract

Theoretical considerations suggest that the temperature distribution within a meter of a cold surface may be partially stratified as a result of radiative and turbulent processes. Even though stratification would be of crucial importance in certain boundary-layer processes, it probably would be undetectable by conventional thermometry. Observations using direct refractive thermometry have been used to determine with great accuracy the temperature distribution above a cold water surface. These observations reveal a persistent temperature anomaly about 10 centimeters above the surface, which is consistent with theory.

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Robert G. Fleagle

Abstract

An equation is derived from the linearized equations of planetary aerodynamics which expresses the vertical component of velocity as a function of baroclinity, static stability, geostrophic vorticity, and geostrophic wind speed toward the north. The properties of this equation are compared with those of other equations and it is concluded that the linear equation provides an insight into the mechanism of large-scale vertical motion and that it is simple enough for easy application to real data. Calculations of vertical velocity using the linear theory are compared with calculations using the adiabatic method, with calculations using two nonlinear methods, and with cloudiness and precipitations. The linear theory yields results which are relatively insensitive to errors in observation and analysis, and which compare favorably with results calculated from other methods. On the other hand, it is not notably more accurate than are other methods; all introduce errors which are comparable to the calculated values.

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Robert G. Fleagle

Abstract

No abstract available.

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