lab_04_meas_uncertainty_w_plots

lab_04_meas_uncertainty_w_plots - Lab 4: Measurement...

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Page 1 of 4 Lab 4: Measurement uncertainty 90 points Introduction: Measurements of weather elements such as temperature, humidity, and wind speed – or any other measurement, for that matter – are subject to several kinds of uncertainty. There might be differences in the type of instrument used, in the accuracy of a particular instrument, and in the response time of the instrument, as well as the precision used by the observer in reading the instrument. Objectives: In this lab we will use temperature measurements to investigate measurement uncertainty. We will (1) find the response time (the “time constant”) for a thermometer; (2) evaluate the variability in observational data; and (3) think about the limitations of observations (response time of instruments, instrument accuracy). Materials: One glass-alcohol thermometer, a cup of ice water, and a watch (or stopwatch) with a second hand or a digital seconds-readout. In Part 1 of this lab, we will find the time constant for a thermometer. The time constant is the amount of time required for a thermometer to reach an arbitrary percentage of a new temperature equilibrium (a state in which the temperature of the thermometer is equal to the temperature of its surroundings). A common definition for the time constant is the time it takes for the thermometer to achieve 63% (1-1/ e ) of a given temperature change. For example, if a thermometer is exposed to a 10 o temperature change, the time constant is the time needed for the temperature to change by 0.63 × 10 o , or 6.3 o . In Part 2 of this lab, we will examine the variability in our estimated time constants by calculating the mean and standard deviation of the data; approximately 67% of the data points will lie within one standard deviation of the mean (either above or below the mean). Procedure:
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This note was uploaded on 10/08/2010 for the course GEOG 1425 taught by Professor Staff during the Fall '08 term at Minnesota.

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lab_04_meas_uncertainty_w_plots - Lab 4: Measurement...

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