Weather parameters

Galloway, J.N. Likens, G.E. Hawley, M.E. Science, 1984,226, pp 829-831. Castillo, R. An Investigation of the Acidity of Stratus Cloud Water and Its Relationship to Droplet Distribution, pH of Rain and Weather Parameters, Ph.D. Thesis, Dept. Atmos. Sci., State University of New York, Albaity, NY, 1979. 

If basic calculations such as those presented are to be conducted, it is important to collect enough weather parameters to calculate reference evapotranspiration ETf). An on-site weather station should be considered a basic requirement minimum sensor requirements to calculate a Penman equation would include solar radiation, wind speed, relative humidity or actual vapor pressure, and air temperature. An on-site rain gauge is essential but it is also a good idea to have a rain gauge on the weather station even if it is not directly on-site. The most accurate variations of the Penman equation calculate Tq on an hourly basis. However, Penman routines using daily summaries are typically satisfactory for the purpose of calculating soil-water recharge. 

Portable weather stations are useful to have available at the field laboratory for acquiring weather data during the course of the worker exposure/re-entry study. There are a variety of portable weather stations available from a variety of suppliers. Weather data to be collected are rainfall, wind direction, wind speed, air temperature, and relative humidity. These electronic weather stations will record the necessary weather parameters on a routine basis. The data are stored and can be transferred to a laptop computer or disk as desired by the Field Scientist. Such portable electronic weather stations are useful during the course of the dislodgeable residue portion of a worker re-entry study when dislodgeable residue samples are taken from remote test sites over the course of a 30-day period. 

Contain a stochastic climate generator capable of simulating daily precipitation and other weather parameters that are similar in amount and statistical variability to historical weather records for the site. 

The instrument for measurement of radon with weather parameters and water use was designed, calibrated and used in the field for 1.5 years with excellent results. The power surge and power interruptions were the only limitations on the use of the instrument. The system software was written mostly during the design phase of the project. However, modifications were made in the software to permit better data collection during power interruptions. Battery backup was needed to keep the data during interruptions of our one week studies. 

Central lo sonic pest inanagemeiil systems is a computerized simulator which, based upon the analysis of hundreds of past observations and experiments, can accept current weather information, fur example, and read out the effects ol the weather parameters. It thus provides directions for whatever pest control actions should or should not be taken at any given lime. In essence, the simulator hikes the place of numerous observers in the field and enables an inlormation center to pass along directives- in real time. A nunther ol factors in addition to weather information, of course, can he input into the sy stem. Needless to say. if such a network were established, all manner of other information pertaining to the crop ecosystem could he handled m addition to pest management data. 

Fig. 1. Global average surface temperatures and atmospheric CO2 levels predicted by models in which CO2 is the only greenhouse gas and the temperature dependence of subaerial silicate weathering is the only effective buffer against changing solar luminosity. One PAL indicates one present atmospheric level of 300 ppm. Curves are labelled by the weathering parameter p (equation (8)). These models are inspired by Walker et al. (1981). Constant CO2 is shown for comparison. Unless silicate weathering is nearly independent of pCQ>2 (P < 0-2), ancient climates are cool.

The network of 211 weather stations allows measurement of tens of basic weather parameters, the most important of which include air temperature, atmospheric pressure, air humidity, wind speed and wind direction. Among the other parameters measured are cloud base height (laser-measured), amount of precipitation (rain or snow), visibility, and air temperature near the ground. Measurements are performed in enclosed areas within the weather stations. 

Polymer type Impurities in polymer Weather parameters... 

However, the three most important factors that have great influence on the performance of polyethylene greenhouse films are weather parameters, stabilization of plastics, and chemical treatment. The effect of these parameters are discussed in detail in the following sections. 

WEATHER PARAMETERS THAT AFFECT PLASTICS LIFETIME... 

Lifetime of polymers exposed to natural euvironmeut cannot be predicted accurately because of complexity of the natural weathering phenomenon and multitude of weather parameters interacting simultaneously [7]. A brief discussion of the important factors that mainly contribute to degradative processes during natural weathering follows. 

Sadot, D. Shamriz, S., Sasson, I., Dror, I., and Kopeika, N. S. (1995). Prediction of overall atmospheric MTF with standard weather parameters Comparison with measurements with two imaging systems. Opt. Eng. 34, 3239-3248. 

The number of studies in this area is limited, but a few have shown exposure of coatings to atmospheric contaminants to be detrimental. Sampers [35] reports that, in a study of polyolefin samples exposed both in Florida and on the Mediterranean coast of France, a dramatic difference was seen in polymer lifetime. Samples exposed on the Mediterranean had only half the life of those in Florida. The two stations had broadly similar weathering parameters the differences should have led to longer lifetimes in France. Sampers concluded that constituents in the rain or wind had chemically interacted with the hindered amine light stabilizers in the polymers exposed in France, causing these samples to be especially vulnerable to UV degradation. 

Having chosen polypropylene (PP) as the material, which does not show sensitivity to moisture, the relevant weathering parameters of the dose-response functions could be limited to spectral irradiance and temperature. 

For plastic materials, it is well known that usually the most important weathering parameters are UV irradiance and temperature P]. Generally, UV radiation initiates photodegradation, whereas temperature influences the kinetics of the autoxidation process ([4], p. 849ff). 

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