Describe in detail the three phases of numerical forecasting
What will be an ideal response?
Answer: The three phases include analysis, prediction, and postprocessing. First is the analysis phase, in which observations are used to supply values corresponding to the starting ("current") state of the atmosphere for all the variables carried in the model. Prediction phase: Fundamentally, the job of a numerical model is to solve the basic equations describing atmospheric behavior. Beginning with values delivered by the analysis phase, the model uses physical equations to obtain new values a few minutes into the future. The process is then repeated, using the output from the first step as input for the next set of calculations. This procedure is performed over and over as many times as necessary to reach the end of the forecast period (24 hours, 48 hours, or whatever). This is called the prediction phase of the model run. This involves many billions of calculations for each time step, despite the fact that there are just a handful of fundamental atmospheric variables (temperature, pressure, wind velocity vector, density, and moisture). Postprocessing phase: The conditions forecast by the model at regular intervals (for example, every 12 hours) are represented on a grid for mapping and other display purposes.
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After the dangers of DDT were recognized, use of toxic organic chemicals in agriculture was virtually eliminated in the United States.
Answer the following statement true (T) or false (F)
The use of plants in the cleansing of water includes all of the following except
A. using gravel-filled basins and wetland plants to treat septic-tank effluent, instead of using a conventional drain field. B. using plant-laden ponds to treat runoff from roads, parking lots and airport runways. C. removing oil from ground water. D. using wetlands to cleanse surface water before it moves into ecologically sensitive estuaries and tidal flats.
Medium-range forecasts
A) are longer in Europe than in the United States. B) typically predict the weather for the next two to four days. C) use essentially the same procedures as short-term forecasting. D) uses statistics rather than a numerical approach.
Discharge permits and the Clean Air Act and Clean Water Act
A) do not allow any wastes to be dumped into natural waterways. B) limit the type but not the amount of wastes dumped into natural waterways. C) limit the amount but not the type of wastes dumped into natural waterways. D) limit the type and the amount of wastes dumped into natural waterways.