Actual Air Temperature Research Articles

Study of mist-cooling for semi-enclosed spaces in Osaka, Japan

Evaporative mist cooling systems are increasingly used in Japan to cool urban spaces as a counter to the urban heat island problem. Japan has a humid climate, which reduces evaporation. The balance between cooling and undesirable wetting requires careful control and placement of misting nozzles. Spraying from varying heights in an atrium showed that a single spray nozzle with Sauter mean droplet diameter of 41 microns can provide cooling of 0.7K without wetting. Cooling effects of mists with larger droplet diameters that cause slight wetting cannot be accurately measured due to the wet bulb effect on the sensors. Simulations suggest actual air temperatures are higher than wet sensor readings. Calculations of effective temperature ET* show that increases in humidity do not overcome the increase in thermal comfort due to the temperature reductions from fine mist.

Performance Study of SPAW Model with Temperature-Derived ET0 as Input in Place of Pan Evaporation under Wheat Crop in a Semiarid Subtropical Climate

In this study, we have attempted to enhance the utility of soil–plant–atmosphere–water (SPAW) model that has been used successfully by various workers in different countries for soil moisture prediction under different cropping conditions. One of the major climatic inputs for SPAW model is pan evaporation, which in many places is not readily available. To address the above, and to get the benefit of this model in regions characterized by limited weather data availability, this study was undertaken using computed ET0 from air temperature by the 1985 Hargreaves equation, as one of the inputs in place of pan evaporation. For the purpose, actual air temperature collected from experimental farm area, as well as forecast air temperature collected from National Centre for Medium Range Weather Forecasting, Government of India, were used. First, the SPAW model was calibrated and its performance was evaluated under wheat, taking layerwise and profile soil moisture as the variables for comparison between the predict...

Dry/Wet Variation and Its Relationship with Regional Warming in Arid-Regions of Northern China

Using the monthly mean air temperature and monthly precipitation data from 60 stations over China, the hydrological processes of surface water budget and evaporation in arid regions of North China are calculated. Based on the computation, the evolutionary rules of surface water and its relationship to temperature change in three northern regions (Northwest, Northeast and North China) are analyzed, especially the relationship between the rule and regional warming. The results indicate that in northern arid regions, surface water has an obviously evolutionary rule with different variations for different areas. However, the relationship between actual evaporation and air temperature demonstrates different phases, and the correlation before 1965 is contrary to that after 1965. The analysis also shows that the current prevalent warming in North China is the main reason for the enhancing trend of aridification.

The (wind) chill factor controlled

The (wind) chill factor controlled

Effects of day and night air temperature in early season on growth, productivity and energy use of spring tomato

Effects of air temperature on tomato (Lycopersicon esculentum Mill) growth, yield and heating energy consumption were investigated in spring of 1993 and 1994. Tomato plants were grown under nine day/night air temperature regimes formed by factorial combination of three day (19, 20 and 21°C) and three night (16, 17 and 18°C) heating temperature set points. Early (until 30 April) fruit yield increased but early fruit size decreased with increasing daily average air temperature (MT, 24-h mean). The plants grown under high daily average air temperature early in the season had lower fruit yield late in the season. Plants grown under high night air temperature (NT) and low day air temperature (DT) during the early production period achieved high fruit yield in early season and avoided the negative effects of high MT on early fruit size; these plants also had high yield and large fruit size late in the season. The different day and night heating temperature regimes studied caused no more than 10% in heating energy use variation. Therefore, for greenhouse tomato production under Great Lakes conditions (approx. 42°N), the optimal day/night air temperature (from January to April) is 20.8–21.0/18.5–19.0°C (actual air temperatures). Key words: Lycopersicon esculentum, tomato, yield, quality, fruit size, daily average air temperature (MT), day-night air temperature difference (DIF), day air temperature (DT), night air temperature (NT)

Formulation of surface heat flux: Application to BOREAS

The aerodynamic temperature is required for prediction of the surface heat flux using Monin‐Obukhov similarity. This “fictitious” temperature is not systematically equal to the actual air temperature near the surface and is not directly available from observations or in numerical models. The aerodynamic temperature is normally replaced with either the canopy air temperature or the surface radiation temperature, sometimes accompanied by adjustment of the thermal roughness length or specification of an excess resistance. In this study, the relationship between the aerodynamic temperature and the surface radiation temperature is examined in terms of the surface energy budget and simple representation of canopy structure. Previous inconsistencies are discussed. The observed behavior of the aerodynamic temperature is studied using Canadian Twin Otter aircraft data from BOREAS over nine different forested and nonforested sites. Variation of the behavior of the aerodynamic temperature between different parts of the boreal forest is found to be strongly correlated with the red reflectance.

Predicting the microclimate inside a greenhouse: an application of a one-dimensional numerical model in an unheated greenhouse

A one-dimensional numerical model has been adapted to predict the microclimate inside an unheated commercial greenhouse during a continuous period of 51 days. The main outputs of the model (hourly air and leaf temperatures and relative humidity) were used to derive the leaf wetness duration (LWD) each day. Measured microclimate parameters inside the greenhouse were used to test the model performance during the corresponding period. Reasonable agreement was found between the predicted and measured parameters for the entire period. The root mean square differences between the predicted and actual air and leaf temperatures, relative humidity and LWD were 1.2 and 1.8°C, 5.8% and 1.9 h d −1, respectively.

Modelling diurnal patterns of air temperature, radiation wind speed and relative humidity by equations from daily characteristics

Calculated data on diurnal patterns from daily averages can be useful as inputs for models simulating plant processes such as photosynthesis and transpiration. A method was developed for the calculation of diurnal patterns of air temperature, wind speed, global radiation and relative humidity from available daily data. Calculated data were validated with measured data collected in Israel, California and The Netherlands. A simple sine-exponential method for describing diurnal air temperature was not sufficient in most cases, and the addition of parameters which specified the time lag of maximum temperature and the effect of buoyancy improved the data accuracy. Diurnal course of wind speed could be described using two sine curves scaled by the measured daily total wind run. Time base of each of the sine curves and the minimum wind speed had to be defined for each location. An accurate description of the diurnal global radiation was obtained, based on the measured daily total global radiation, and the calculated sine of the solar elevation corrected for atmospheric transmissivity. Relative humidity was calculated from the dew point temperature computed as the minimum value of a characteristic seasonal value or the actual air temperature. When the site-specific parameters were known or correctly estimated these methods gave good estimations of the diurnal weather patterns.

Surface cooling due to forest fire smoke

In four different cases of extensive forest fire smoke the surface temperature effects were determined under the smoke cloud. In all cases, daytime cooling and no nighttime effects were found. The locations of smoke clouds from extensive forest fires in western Canada in 1981 and 1982, in northern China and Siberia in 1987, and in Yellowstone National Park in northwestern Wyoming in 1988 were determined from satellite imagery. As these smoke clouds passed over the midwestern United States for the Canadian and Yellow‐stone fires and over Alaska for the Chinese/Siberian fires, surface air temperature effects were determined by comparing actual surface air temperatures with those forecast by model output statistics (MOS) of the United States National Weather Service. MOS error fields corresponding to the smoke cloud locations showed day‐time cooling of 1.5° to 7°C under the smoke but no nighttime effects. These results correspond to theoretical estimates of the effects of smoke, and they serve as observational confirmation of a portion of the nuclear winter theory. This also implies that smoke from biomass burning can have a daytime cooling effect of a few degrees over seasonal time scales. In order to properly simulate the present climate with a numerical climate model in regions of regular burning it may be necessary to include this smoke effect.

Estimating Manure Temperatures from Air Temperatures and Results of Its Use in Models of Filth Fly (Diptera: Muscidae) Development

Populations of the house fly, Musca domestica L., and other filth flies and their natural enemies in confined-animal houses are greatly influenced by the temperature of their manure habitat. In order to use filth fly management simulation models that are driven by habitat temperatures, a mathematical relationship between manure temperature and air temperature, time of day, and manure depth was developed based on simultaneous hourly measurements of air and manure temperatures at depths of 1, 7, and 15 cm in three poultry housing environments over a three year period. Manure moisture had no measurable effect on manure temperature. A simulation model predicting population sizes of the house fly and a predaceous mite was driven using temperatures from the equation, and actual air and manure temperature recordings. Predicted population sizes using the estimated manure temperatures were closer to the sizes using actual manure temperatures than the sizes using air temperatures.

Thermal interaction between animal and microclimate: Specification of a “standard environmental temperature” for animals outdoors

An index is developed from heat transfer theory to describe the thermal environment experienced by animals outdoors. This index, termed the “standard environmental temperature”, is defined as the air temperature in an isothermal laboratory where the walls are at air temperature and there is no sunlight, and at which temperature the total rate of heat loss from the body surface is the same as in the actual environment. Standard values are assumed for the humidity and convection conditions in the laboratory. Values of standard environmental temperature are presented for cattle exposed to sunlight, wind and different humidities outdoors. These values can be more than 15°C above or below the actual air temperature, depending on the conditions.

Heat flux and surface temperature variations in an unconditioned room of brick masonry construction in a composite climate

This paper analyses the temperatures of different internal surfaces and the heat flow into an unconditioned room located in the top floor of a brick masonry residential building in Delhi. The experimental investigation which included the measurement of surface temperatures and heat flow are described. The two methods of analysis, namely, admittance and transmission matrix methods, with the necessary modifications made for this study, are mentioned. The results showing the comparison between the measured surface temperatures and actual room air temperatures, for three different seasons, are presented and discussed. Similarly, results showing the comparison between the measured heat flow and predicted heat flow by both methods, in all seasons, are presented and discussed. The conclusions show that both the admittance and transmission matrix methods predict the heat flow well during steady cyclic periods. During a persistent unsteady regime, the transmission matrix method could predict values of heat flow slightly better compared to the admittance method. In general, the admittance method predicts a more dampened system.

Predicting the date of harvest of vining peas by means of air and soil temperature sums and node countings

Predictions of the date of harvest of vining peas ( Pisum sativum L.) were performed by means of statistical models. Simple models based on sowing-to-harvest prediction criteria and two-component models based on a combination of sowing-to-emergence and emergence-to-harvest prediction criteria were applied. The criteria used were number of days, and soil and air temperature sums, with base temperature in the range 2.6–3.8°C and 3.0–6.0°C, respectively. The best predictions of the harvest date were obtained with two-component models, and sowing-to-emergence predictions criteria based on soil temperature were better than others examined. Among two-component models, the smallest error of prediction-2.4 days-was obtained with the model using sowing-to-emergence soil temperature sums with base temperature 3.0°C, and emergence-to-harvest number of days as prediction criteria. The prediction model traditionally used in practice applies sowing-to-harvest air temperature sums with base temperature 4.5°C as prediction criterion, and the error of prediction of this model was 4.3 days. Close linear relationships were found between number of nodes and air temperature sums accumulated from sowing or emergence. In consequence, the number of nodes is a reliable indicator of the actual air temperature sum status of the crop. Some practical aspects of applying two-component models and node counting for predicting the date of harvest of vining peas are discussed.

事務所ビル室内における温度・気流分布の実態とその評価 : 室内熱環境の品質実態(その2)

The actual room air temperature distribution and air-movement have been researched in four office spaces together with an investigation of the views of the occupants with regard to this aspect of comfort. The results show that (1) To restrict complaints about the thermal environment to less than 20 %, room air temperature should be kept below 26℃ when cooling. (2) Vertical gradient of room air temperature increases during heating. To restrict complaints to less than 20 %, a consideration in room environmental design is to maintain the air temperature at floor level (0.1 m above the floor) higher than 21℃ and at head level (1.1 m above the floor) lower than 25℃. (3) To control the vertical gradient of room air temperature, it is important to avoid the excessive declease of floor surface temperature when heating is stopped. (4) Information has been given on the relationships between sensation of air-movement and discomfort, and between room air temperature and desirable air-movement.

Long-wave radiative flux divergence and nocturnal cooling of the urban atmosphere

Measurements of long-wave radiative flux divergence in the vertical were obtained from an above roof-level site in the urban area of Montreal, P.Q. Radiative flux divergence was observed in the 4–5.5 m layer above the roof on almost all occasions, but especially with weak air flow. Radiative cooling rates calculated from the radiation measurements were greater than actual air temperature cooling rates, and in reasonable agreement with previous rural results. The importance and implications of these findings in urban meteorology are discussed.

Refractive temperature

Refraction tables used in navigation and surveying are almost all derived from those of Bessel, whose computations, based on English star observations, assume that atmospheric temperature decreases with height at the rate of about 0.6 F.° per 1,000 ft. Neither this assumption nor that of any subsequent investigator is entirely in accord with present-day knowledge of atmospheric structure, which generally has a temperature decrease of around 3 F.° per 1,000 ft. to the tropopause, with widely varying conditions above it. The Bessel tables in general use cannot be extrapolated for surface air temperatures much different from 50° F.; in particular, for extreme cold conditions it is desirable to use, in place of the actual air temperature, the refractive temperature, which is that temperature for which the refraction correction given in the tables equals the correction which is actually required, and which may be estimated from general climatic considerations.