Search Results

You are looking at 1 - 10 of 72 items for

  • Author or Editor: J. Neumann x
  • Refine by Access: All Content x
Clear All Modify Search
J. Neumann

Abstract

A method is described for calculating mean values of some meteorological elements for the periods sunrise to sunset, and sunset to sunrise, respectively. The method is simple to apply and requires relatively few data, provided that the diurnal variation of the element concerned may be adequately represented by the first two Fourier waves. The method takes full account of the date of the day and the latitude of the station for which the mean values are desired.

A nomogram is presented to aid computation of the relevant mean values.

Full access
J. Neumann

Abstract

Abstract not available.

Full access
J. Neumann

Abstract

Full access
J. NEUMANN

Abstract

An empirical method described by Klein is applied to calculate insolation for the Lake Hefner, Okla., area for 1 year of the Lake Hefner Studies. For some of the months, the computed values show unsatisfactory agreement with the observed amounts, but the computed annual total is in close accord with the observed annual total.

It is suggested that agreement between the monthly values may be improved by introducing a curvilinear regression in the formula whereby account is taken of the depletion of insolation by sky coverage.

Full access
J. NEUMANN

Abstract

Assuming a simple pyrheliometric station model, an equation is derived relating the amount of insolation Q from a sky whose fraction C is covered by clouds, to the insolation Q 0, arriving at the same surface from a cloudless sky. The equation is of the form

Q/QO=1-(A-a)(1+a)C,

where A is the sum of cloud albedo and absorptivity expressed as fraction of the radiation incident on cloud tops and the symbol a represents the depletion coefficient of insolation in cloudless air in the layer between cloud top and cloud base levels.

The theoretical equation resembles the empirical equation Q/Q 0=1−kC where k is supposed to be a constant. The theoretical equation shows the dependence of k on relevant physical variables.

It is shown that the theoretical equation combined with results of pyrheliometric observations, from which a value of k has been deduced, leads to a value of A which is in close accord with its value obtained by independent methods. On the other hand, if we assume reasonable values for A and a, the resulting value for k is in good agreement with the best value found from pyrheliometric observations.

Full access
J. Neumann

Abstract

No Abstract Available.

Full access
J. Neumann

Abstract

No Abstract Available

Full access
J. Neumann

Abstract

Full access
J. Neumann

In the summer of 1657, Denmark launched hostile actions against Sweden. Charles X, king of Sweden, who at the time was engaged in a war in Poland, marched his army at great speed to Jutland, the westernmost part of Denmark. The conquest of Jutland was completed in November 1657, but in the absence of an adequate naval force, Charles X could not carry his campaign to Zealand, the island on which Copenhagen is situated. Unexpectedly, the severe winter of 1657–58 came to his aid. In February 1658 the Little Belt (separating Jutland from the island of Fünen) as well as the Great Belt (separating Fünen from Zealand) froze over completely and, apparently, to a sufficient depth that the Swedish Army was able to cross over the frozen sea areas from Jutland to Zealand and force the Danes to sue for peace. Ice also played a major role in earlier Scandinavian history.

Some excerpts are cited from contemporary literature (and diaries) describing the harshness of the winter of 1657–58 in other European countries. Not only rivers, including major rivers, and lakes froze over but also the coastal waters of Flanders and the Netherlands as well as the Danish sea areas. An estimate of the air temperature of the winter of 1657–58 in the Netherlands is also given.

Full access
J. Neumann

Abstract

In the equation for the concentration of pollutants from a steady continuous point source, in a stationaryturbulent flow, the factor 1/u enters (u is the mean wind for a given stationary situation). If we are interestedin the concentration along a given wind direction and u denotes the wind speed in that direction and if weseek the average concentration for a class of flow situations (e.g., for the class of statically stable flows),each member of the class representing an individual stationary situation, then the averaging to be appliedis to 1/u and not to u. On the assumption (verified by some examples) that the distribution of u isa "humped" gamma distribution (standard deviation σ less than the average u of u for the class as a whole),we show that the average of 1/u equals 1/(u[1-(σ/u)2]}. Thus the average of 1/u is greater than 1/uand the resulting concentration estimate is larger than the one that would be obtained by the incorrect useof 1/u.

Full access