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Robert W. Lenhard Jr.

The relationship between the weight of glaze on power lines and common meteorological variables is examined. The icing data used are those collected by the Pennsylvania Electric Association; the meteorological data are those available in third-order climatological station records. A graphical correlation between ice weight, daily precipitation total and a derived temperature variable is obtained. In addition, the regression of ice weight on daily precipitation is explored and the probability of occurrence of daily maximum and minimum temperatures associated with glaze storms is given. These two relations are suggested as alternative estimating tools.

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Robert W. Lenhard Jr.

Abstract

The accuracy with which meteorological elements can be measured by currently operational radiosonde equipment is examined and representative error values calculated. A method of analyzing cross-sections for missile test ranges is described. The average of two soundings is plotted at the mid-point between them and the soundings reconstructed by use of the geostrophic extrapolation. The gain in accuracy from averaging is offset by the geostrophic approximation. These opposing effects are shown by error values calculated for a fixed range distance and by distance values over which the analysis is useful.

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Robert W. Lenhard

Abstract

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Robert W. Lenhard

Paired, simultaneous, AN/GMD-1 radiosonde flights released 10 to 12 miles apart show smaller differences in heights of pressure surfaces than would occur if previous estimates of radiosonde error are accepted. The radiosonde system apparently delivers temperature information accurate to 0.3C (RMS error), exclusive of the solar radiation and response time errors of the thermistor. A table of errors for computed values of height and density at specified pressure, and of pressure at specified height is presented, based on this temperature accuracy.

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Robert W. Lenhard

Abstract

The variability of wind with distance over New England during the period January–March, 1969, is compared to some general models and found to be larger than the models would predict. The difference is not unreasonable considering the location and the amount of cyclonic activity.

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Robert W. Lenhard and Werner A. Baum

Abstract

The concept of a satisfactory normal monthly temperature is considered. January and July mean temperature records at seven stations in the United States are examined. It is found that, except in the western United States in summer, such temperature records may be accepted as constituting a random sample. It is also found that, in general, mean monthly temperatures are not normally distributed.

The method of confidence limits is applied to determination of a satisfactory normal temperature. Seasonal and geographical variations in reliability of normal temperatures are observed. Consideration is given to the adequacy with which the normal characterizes the temperature record, and to the influence of trends and cyclic fluctuations on this adequacy. It is suggested that a normal of desired reliability be computed from the most recent portion of the record to be most representative.

In general, normals computed for different periods of record will differ; but these differences may have little practical significance when the magnitude of the effect is considered relative to the requirements of the application.

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Robert W. Lenhard Jr., Arnold Court, and Henry A. Salmela

Abstract

The time-lag variability of winds at 3,6,9 and 12 km, observed at approximately 1-hr intervals over Bedford, Mass., during the first week of April 1960 is proportional to the square root of the time lag. The proportionality factor varies with mean wind speed, and perhaps also with altitude, thus differing from the average value found by previous investigators. Of the other sources of variability present in this unique series, deviations from precise 1-hr intervals were most important; less important, but still significant, were difference in the exact balloon positions when successive measurements were made, and in the exact heights to which they applied.

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Captain Robert W. Lenhard Jr. and T/Sgt John M. Foard

A method is presented for determining the probability of occurrence of all combinations of crosswind and runway wind components at an airport. It is applied to Prestwick, Scotland for the existing instrument runway and for winds occurring with ceilings less than 1000 ft and/or visibilities less than three miles.

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