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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.
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.
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Abstract
The absorption spectra of 49% 73% and 98% sulfuric acid water solutions for wavelengths of 0.3–6.5.μ and those of ammonium sulfate for 0.3–25 μ are either measured for the purposes of this study or quoted from the literature. Sulfuric acid water solutions have an absorption in the range 1.6–6.5μ. Absorption by 49% and 73% solutions is particularly strong. It is much stronger than absorption by liquid water over most of the range. Ammonium sulfate has no absorption of any significance from 0,3 to 2.85μ but has four absorption bands in the range 2.85-25μ, the largest absorption occurring at about 9.25μ in the terrestrial radiation “window.”
The conclusions are as follows: 1) sulfuric acid water solution droplets will absorb solar radiation in the near IR, about 2μ 2) ammonium sulfate particles will not absorb solar radiation; and 3) both will, of course, scatter solar radiation.
The above results are relevant to the absorption of solar radiation by droplets or by solid particles in the lower stratosphere as well as to a similar absorption in the lower atmosphere of industrially polluted areas.
Abstract
The absorption spectra of 49% 73% and 98% sulfuric acid water solutions for wavelengths of 0.3–6.5.μ and those of ammonium sulfate for 0.3–25 μ are either measured for the purposes of this study or quoted from the literature. Sulfuric acid water solutions have an absorption in the range 1.6–6.5μ. Absorption by 49% and 73% solutions is particularly strong. It is much stronger than absorption by liquid water over most of the range. Ammonium sulfate has no absorption of any significance from 0,3 to 2.85μ but has four absorption bands in the range 2.85-25μ, the largest absorption occurring at about 9.25μ in the terrestrial radiation “window.”
The conclusions are as follows: 1) sulfuric acid water solution droplets will absorb solar radiation in the near IR, about 2μ 2) ammonium sulfate particles will not absorb solar radiation; and 3) both will, of course, scatter solar radiation.
The above results are relevant to the absorption of solar radiation by droplets or by solid particles in the lower stratosphere as well as to a similar absorption in the lower atmosphere of industrially polluted areas.
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.
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.
Abstract
Attention is drawn to the observational fact that the rate of turning of the direction of sea and land breezes is far from uniform over the diurnal cycle. A theoretical analysis of the problem is then undertaken for a two-dimensional sea and land breeze model. It is shown that the rate of local turning equals the sum of three principal terms. The first term is −k f (f = Coriolis parameter, k = vertical unit vector), a term known from previous theoretical work; the second is the cross product of the horizontal mesoscale pressure gradient (approximately equivalent to the diurnal heating/cooUng of the land relative to the sea) and the velocity of the breezes; the third involves the cross product of the horizontal large-scale pressure gradient, assumed not be affected by the diurnal beating, and the aforementioned velocity. All three terms represent rotation about the vertical but, while the first term is a constant, the other two are variable both in magnitude and sign. These two variable terms modulate the rate of turning in an important manner. Finally, the theoretical predictions are compared with observations and special situations are studied.
Abstract
Attention is drawn to the observational fact that the rate of turning of the direction of sea and land breezes is far from uniform over the diurnal cycle. A theoretical analysis of the problem is then undertaken for a two-dimensional sea and land breeze model. It is shown that the rate of local turning equals the sum of three principal terms. The first term is −k f (f = Coriolis parameter, k = vertical unit vector), a term known from previous theoretical work; the second is the cross product of the horizontal mesoscale pressure gradient (approximately equivalent to the diurnal heating/cooUng of the land relative to the sea) and the velocity of the breezes; the third involves the cross product of the horizontal large-scale pressure gradient, assumed not be affected by the diurnal beating, and the aforementioned velocity. All three terms represent rotation about the vertical but, while the first term is a constant, the other two are variable both in magnitude and sign. These two variable terms modulate the rate of turning in an important manner. Finally, the theoretical predictions are compared with observations and special situations are studied.
Heat balance considerations indicate that the annual amount of evaporation from an extensive water surface is greater by some 33 percent than evapotranspiration from an extensive vegetation-covered land surface having an ample supply of water. The assumption is that the same amount of insolation reaches both surfaces. Turbulence theory is used to show that the above estimate leads to values of the friction velocity (or shearing stress) which are in close agreement with independent results for vegetation-covered land surfaces, indicating the correctness or approximate correctness of the above estimate. The assumption of the demonstration is that the geostrophic wind is the same over both surfaces. It is estimated that the annual amount of sensible heat transferred from the vegetation-covered land surface is some 5 to 10 percent of the insolation reaching that surface.
Heat balance considerations indicate that the annual amount of evaporation from an extensive water surface is greater by some 33 percent than evapotranspiration from an extensive vegetation-covered land surface having an ample supply of water. The assumption is that the same amount of insolation reaches both surfaces. Turbulence theory is used to show that the above estimate leads to values of the friction velocity (or shearing stress) which are in close agreement with independent results for vegetation-covered land surfaces, indicating the correctness or approximate correctness of the above estimate. The assumption of the demonstration is that the geostrophic wind is the same over both surfaces. It is estimated that the annual amount of sensible heat transferred from the vegetation-covered land surface is some 5 to 10 percent of the insolation reaching that surface.
