England-2011-lab2-yellow
Lab 2: Holy Pigeon P$#! Batman, it's Penelope Poison!
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Problem Description and Approach
Our task as the Yellow Team was to collect data on various water bodies in London in order to gauge the possible effects of releasing a toxic substance into London’s water supply. Dr. Obfuscation only provided photographs of the 11 locations where Penelope Poison threatened to release the toxic substances. We needed to figure out the geographical coordinates (latitude and longitude) of these locations, measure the air and water temperature, our elevation and note the wind speed plus direction at the times we are at these locations Most importantly, we needed to figure out what the most accurate approach to collecting this data was, and what if any flaws there were in collecting this data. Time was also a factor to keep in mind, so we decided to tackle the location not in alphabetical order, but in the order of their proximity to one another.
Nowadays there are more data stored in a single photo than visual photo itself. Data like when photo was taken, which equipment was used… Moreover if the camera has GPS it can also store the coordinates from where the picture was taken (geocoding). So we uploaded all pictures to the software called Picasa that allowed us to further integrate those pictures to the Google Earth, after this we were ready for our journey.
Data Collection
Latitude, Longitude and Elevation
In order to determine the latitude, longitude and the elevation we used GPS device Garmin, the Etrex Vista C. The way we measured was very simple. After turning it on, we would wait for a few moments for the GPS to recognize enough satellites and after that we would take the readings. By flipping and turning the GPS around we would get the second and the third reading.
Wind direction using a compass and Tesco plastic bag
We laid the compass on a flat surface (on the hand, on the ground, on top of the bench and many places) to help us determine the direction (north, west, east and south) of our spot; we did this for every location A-K. Three of the group members would each stand parallel to the compass with the plastic bag on their hand and observe the direction of the wind. We tried to change people doing this procedure for every location.
Wind speed using the Beaufort Scale
Air and Water Temperature using the Maplin thermocouple thermometer
In order to measure the temperature for the air and water we used the Maplin thermocoupla thermometer device provided to us by Charlie Peck. This device consists of a screen for taking readings, an on and off button, a hold button, and a small metal rod attached to a wire on the back of the device for taking temperature measurements. At each location we went to we took out the rod, turned on the device, left it on for two minutes and then took the reading, copied the temperature reading onto our data sheet, then turned off the device for one minute and repeated this process twice more copying the respective readings onto our notes. Then using the same tool we put the small rod into the water at each location, here it was important to make sure the rod was immersed significantly in the water, we left the rod for two minutes, removed it from the water and copied the temperature from the screen. We then dried off the rod waited one minute and repeated this process twice.
Data Analysis
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Error Analysis
Latitude, Longitude and Elevation
We checked on the Garmin website, the Etrex Vista C, is accurate within 30 meters and 95% of the time. Its accuracy and errors also largely depends on how many satellites it can find.
Wind Direction using a compass and Tesco plastic bag
It was hard having the compass on a flat surface in some areas as most readings were taken while it was on someone's palm ( a surface that is not even). In addition, regular compasses are not made to point exact North, but relative North which a point with a particularly strong magnetic pull. Therefore many of the objects we identified as being North or South of the water bodies might not have been so, if we were looking for a precise bearings. When experiencing light winds, a Tesco plastic bag might prove to be denser than the wind thus making it impossible to show which direction the wind is moving. Using objects that have a similar density to air, such as dyed smoke or cigarette smoke might be more efficient in showing much lighter winds.
Wind Speed using the Beaufort Scale
Air and Water Temperature using the Maplin thermocouple thermometer
Sources of error that we experienced in collecting air and water temperature were both mechanical and human errors. Although we dried the rod after each reading the rod may still have been chilled which may have affected the results of the next air temperature reading. As far as documenting water temperatures we experienced problems with accuracy due to an inability in some locations to immerse the rod without it being in contact with stone. Also the varying depth of the bodies of water may have had some effect on the accuracy of the readings. In the manual of this device it is written that its error is +- 3%.
Images
Below is a link that will take you to the premier showing of the Yellow Team's first production (in the form of a slide show) of Holy Pigeon P#$@ Batman, it's Penelope Poison!. Accompanying each picture is a caption including what is North and South of the water body.
Appendix A: Raw Data
| Location: | Time | GPS Elevation | Air Temp | Water Temp | Wind Direction | Wind Speed | Latitude | Longitude |
|---|---|---|---|---|---|---|---|---|
| H | ||||||||
| H | ||||||||
| H | ||||||||
| H | ||||||||
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Appendix B: Visualization
Appendix C: Who Did What
Eva Marengo My contribution to the lab was taking the water and air temperature readings and helping record the data. At each location I took three readings of the water and of the air. In the lab report I did the associated write up. I also assisted at navigation and finding the perspective of the photos taken in order to replicate them.
Vivian Bateyunga My contribution to the lab was collecting data on wind direction using a basic compass and a Tesco plastic bag. I also described what was North and South of the location of the water body. I assisted with copy-editing the lab write up and figuring out the averages for the raw data collected.
Sandra Mamus Ngeseyan I was the principle data-recorder for the group and also helped determine what the wind-speed at each location was. It was extremely important that my handwriting was neat and the recording of data was done in an organized fashion. I helped to write up the description of the lab, as well as gather information from different members of the group.
