Accurate expressions for the dew point and frost point derived from the Rankine-Kirchhoff approximations

2021 ◽  
Author(s):  
David M. Romps
Keyword(s):  
Relative Humidity ◽  
Specific Volume ◽  
Full Range ◽  
Ideal Gas ◽  
Heat Capacities ◽  
Dew Point ◽  
Laboratory Measurements ◽  
Physical Constants ◽  
Frost Point ◽  
Analytic Expressions

AbstractAccurate, explicit, and analytic expressions are derived for the dew point and frost point as functions of temperature and relative humidity. These are derived theoretically in terms of physical constants using the Rankine-Kirchhoff approximations, which assume an ideal gas, fixed heat capacities, and zero specific volume of condensates. Compared to modern laboratory measurements, the expressions are accurate to within a few hundredths of a degree over the full range of Earth-relevant temperatures, from 180 to 273 K for the frost point and 230 to 330 K for the dew point.

scholarly journals Advancements, measurement uncertainties, and recent comparisons of the NOAA frost point hygrometer

2016 ◽  
Vol 9 (9) ◽  
pp. 4295-4310 ◽  
Author(s):  
Emrys G. Hall ◽  
Allen F. Jordan ◽  
Dale F. Hurst ◽  
Samuel J. Oltmans ◽  
Holger Vömel ◽  
...  
Keyword(s):  
Water Vapor ◽  
Full Range ◽  
Dew Point ◽  
Tunable Diode Laser ◽  
Stratospheric Water Vapor ◽  
Laser Absorption ◽  
Frost Point ◽  
High Level ◽  
Diode Laser Absorption ◽  
Good Agreement

Abstract. The NOAA frost point hygrometer (FPH) is a balloon-borne instrument flown monthly at three sites to measure water vapor profiles up to 28 km. The FPH record from Boulder, Colorado, is the longest continuous stratospheric water vapor record. The instrument has an uncertainty in the stratosphere that is  <  6 % and up to 12 % in the troposphere. A digital microcontroller version of the instrument improved upon the older versions in 2008 with sunlight filtering, better frost control, and resistance to radio frequency interference (RFI). A new thermistor calibration technique was implemented in 2014, decreasing the uncertainty in the thermistor calibration fit to less than 0.01 °C over the full range of frost – or dew point temperatures (−93 to +20 °C) measured during a profile. Results from multiple water vapor intercomparisons are presented, including the excellent agreement between the NOAA FPH and the direct tunable diode laser absorption spectrometer (dTDLAS) MC-PicT-1.4 during AquaVIT-2 chamber experiments over 6 days that provides confidence in the accuracy of the FPH measurements. Dual instrument flights with two FPHs or an FPH and a cryogenic frost point hygrometer (CFH) also show good agreement when launched on the same balloon. The results from these comparisons demonstrate the high level of accuracy of the NOAA FPH.

scholarly journals Solar Radiation, Air Temperature, Relative Humidity, and Dew Point Study: Damak, Jhapa, Nepal

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Arun Kumar Shrestha ◽  
Arati Thapa ◽  
Hima Gautam
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Air Temperature ◽  
Gaussian Function ◽  
Great Influence ◽  
Dew Point ◽  
Upward Trend ◽  
Summer Maximum ◽  
Online Calculator ◽  
Climatic Phenomenon

Monitoring and prediction of the climatic phenomenon are of keen interest in recent years because it has great influence in the lives of people and their environments. This paper is aimed at reporting the variation of daily and monthly solar radiation, air temperature, relative humidity (RH), and dew point over the year of 2013 based on the data obtained from the weather station situated in Damak, Nepal. The result shows that on a clear day, the variation of solar radiation and RH follows the Gaussian function in which the first one has an upward trend and the second one has a downward trend. However, the change in air temperature satisfies the sine function. The dew point temperature shows somewhat complex behavior. Monthly variation of solar radiation, air temperature, and dew point shows a similar pattern, lower at winter and higher in summer. Maximum solar radiation (331 Wm-2) was observed in May and minimum (170 Wm-2) in December. Air temperature and dew point had the highest value from June to September nearly at 29°C and 25°C, respectively. The lowest value of the relative humidity (55.4%) in April indicates the driest month of the year. Dew point was also calculated from the actual readings of air temperature and relative humidity using the online calculator, and the calculated value showed the exact linear relationship with the observed value. The diurnal and nocturnal temperature of each month showed that temperature difference was relatively lower (less than 10°C) at summer rather than in winter.

Gas permeability calculation of tight rocks based on laboratory measurements with non-ideal gas slippage and poroelastic effects considered

2018 ◽  
Vol 112 ◽  
pp. 16-24 ◽  
Author(s):  
Ziyan Wang ◽  
Reinhard Fink ◽  
Yue Wang ◽  
Alexandra Amann-Hildenbrand ◽  
Bernhard M. Krooss ◽  
...  
Keyword(s):  
Gas Permeability ◽  
Ideal Gas ◽  
Laboratory Measurements ◽  
Gas Slippage ◽  
Tight Rocks

The Cause and Forecasting of Ice Fogs *

1953 ◽  
Vol 34 (9) ◽  
pp. 397-400 ◽  
Author(s):  
H. Appleman
Keyword(s):  
Relative Humidity ◽  
Low Temperature ◽  
Combustion Process ◽  
Hydrocarbon Fuels ◽  
Dew Point ◽  
The Other ◽  
Sudden Increase ◽  
Minimum Frequency ◽  
Ice Fog ◽  
Rare Phenomenon

Studies carried out in Alaska and Canada have shown that fog is a relatively rare phenomenon at temperatures between 0° and − 30°F, with a minimum frequency between − 20° and −30°. At still lower temperatures, however, the frequency of fog increases rapidly. This effect is noted only in the immediate vicinity of inhabited areas, such as towns and airfields. The reason for the sudden increase in fog frequency at these temperatures, and the rarity or lack of fog at the higher temperatures, has not been heretofore explained. In a recent study on aircraft condensation trails, it was shown that if the temperature is sufficiently low (between − 20 and − 40°F, depending on the relative humidity), the burning of hydrocarbon fuels, such as would occur in towns and at airfields, easily results in supersaturation of the air and a “surface contrail” or ice fog. At higher temperatures, on the other hand, combustion actually reduces the relative humidity of the atmosphere, hindering the formation of fog. In this paper it is shown that low-temperature (ice) fogs form as a result of the combustion process, and curves are presented showing the temperature-dew-point relationship necessary for the formation of such fogs.

scholarly journals Optimization of bioinspired triangular patterns for water condensation and transport

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190127 ◽  
Author(s):  
Dong Song ◽  
Bharat Bhushan
Keyword(s):  
Relative Humidity ◽  
Pressure Gradient ◽  
Surface Temperature ◽  
Dew Point ◽  
Laplace Pressure ◽  
Theme Issue ◽  
Water Condensation ◽  
Water Collection ◽  
Condensed Water ◽  
Droplet Condensation

Water condenses on a surface in ambient environment if the surface temperature is below the dew point. For water collection, droplets should be transported to storage before the condensed water evaporates. In this study, Laplace pressure gradient inspired by conical spines of cactus plants is used to facilitate the transport of water condensed in a triangular pattern to the storage. Droplet condensation, transportation and water collection rate within the bioinspired hydrophilic triangular patterns with various lengths and included angles, surrounded by superhydrophobic regions, were explored. The effect of relative humidity was also explored. This bioinspired technique can be used to develop efficient water collection systems. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

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