lab_01_WB_measurements_with_table

lab_01_WB_measurements_with_table - Lab 1: West Bank...

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Page 1 of 7 Lab 1: West Bank weather observations 100 points Introduction: Values of meteorological variables can change over short distances, especially in areas with complex terrain and vegetation patterns. Official measurements made by the National Weather Service make point observations for large spatial areas. Sometimes these measurements are not representative of some nearby places. Objective: Using some basic meteorological instruments, we will measure and analyze spatial variability in temperature, humidity, and wind speed at different sites on the West Bank. Materials: An infrared (IR) thermometer, a sling psychrometer, a propeller anemometer, and a timer or watch with a second hand. Thermometer: Liquid-in-glass thermometers indicate temperature by the expansion of the fluid in the bulb. As temperatures rise, the fluid is forced up the capillary tube; when temperatures fall, the liquid contracts and the fluid moves back down the tube toward the bulb. The tube is calibrated against an established scale to indicate the temperature. An IR thermometer, on the other hand, takes advantage of the fact that every object that has a ‘temperature’ emits energy. The IR thermometer measures the amount of energy being emitted by an object, and uses the relationship between energy and temperature (described by the Stefan-Boltzmann law – see Chapter 2 of the text) to determine the temperature of that object. Psychrometer: This instrument is used to determine the relative humidity. A dry-bulb (i.e., regular) thermometer gives the current air temperature. A wet-bulb thermometer has a cloth wick tied around the end, which then is saturated with water. As air blows air over the wick, the water evaporates and thus cools the thermometer. The amount of cooling that takes place is directly proportional to the dryness of the air: the larger the difference between the wet- and dry-bulb temperatures, the lower the
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This note was uploaded on 10/08/2010 for the course PSY 3001w taught by Professor Stellmack during the Fall '10 term at Minnesota.

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lab_01_WB_measurements_with_table - Lab 1: West Bank...

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