## Case Study – Post 16 – INS Guindabols – Lleida, Spain

### Study of the Atmosphere by using the Data collected by a Weather Balloon

The students of Baccalaureate attended the launching to the stratosphere of a weather balloon on the 19th April 2018. The balloon was equipped with different kinds of sensors and electronic devices, such as a GPS, a radio set, and a webcam.

By using this balloon, students undertook their research related to the atmosphere data which had been collected by the sensors.

### Define the problem

The students worked in groups of 4-5, and with the teachers’ help, they first explored the following questions:

• How will some physical magnitudes change with height?
• How will radioactivity change with height? Why? How will the movement of the balloon be when it rises? And when will it go down?
• Can the wind speed be measured?
• How can be the Earth’s Albedo determined?
• They also investigated the following questions using images taken from the equipped camera.
• Can the most characteristic geographic peaks in the Pyrenees be recognised?
• Why is the sky black?

This photo shows the curvature of the Earth.

• Can you think of any experiment to prove that the earth is spherical?
• How would you make an estimate length of the radius of the Earth from the image?
• Which day and where could the weather balloon be launched?
• How can the route be predicted? Where will the balloon fall?

After the brainstorming of the problems, the students decided to explore:

### Explore the problem

They then started investigating these problems:

• Which data are needed in order to solve the research question?
• Which graphic representation is more appropriate?
• Which statistical treatment is most suitable?

Click to enlarge

Click to enlarge

The table shows the data obtained by the different sensors:

 TIME (min) HEIGHT (m) INTERN TEMP.(Cº) EXTERN TEMP. (Cº) DIRECTION (º) SPEED (km/h) 0 13141 9 11 247 26 1 13504 8 -32 302 37 2 13911 8 -32 277 37 3 14294 7 -32 286 43 4 14693 7 -32 288 15 5 15075 7 -31 54 15 6 15480 6 -31 314 9 7 15834 6 -30 279 20 8 16221 5 -30 35 24 9 16573 5 -29 138 19 10 16937 5 -28 267 24 11 17304 4 -28 3 22 12 17656 4 -28 342 24 13 18023 4 -28 31 20 14 18393 4 -27 38 19 15 18768 4 -26 40 20 16 19153 3 -26 280 2 17 19534 3 -25 131 15 18 19913 3 -25 235 33 19 20297 3 -24 310 7 20 20693 3 -24 173 35 21 21099 2 -24 315 7 22 21455 2 -25 217 17 23 20313 2 -36 209 24 24 19284 2 -38 279 28 25 17364 2 -44 257 41 26 16495 2 -46 250 30 27 15668 1 -48 273 26 28 14823 1 -48 355 41 29 14013 1 -49 236 30 30 13255 0 -51 224 20 31 12564 0 -51 250 70 32 11906 0 -51 296 115 33 11280 -1 -50 287 137 34 10683 -2 -47 273 128 35 10104 -3 -44 294 119 36 9552 -4 -41 274 52 37 9025 -4 -38 241 31 38 8526 -5 -35 236 48 39 8037 -6 -31 216 33 40 7574 -6 -27 284 33 41 7132 -7 -23 242 52 42 6680 -7 -20 207 37 43 6221 -7 -17 249 52 44 5769 -7 -14 240 48 45 5364 -7 -10 226 50 46 4976 -7 -7 238 50 47 4601 -7 -5 232 37 48 4230 -6 -4 249 41 49 3832 -6 -2 283 54 50 3454 -5 0 304 24 51 3088 -4 1 271 30 52 2754 -4 2 264 37 53 2165 -2 4 318 35 54 1854 -1 6 291 46 55 1553 0 8 298 28 56 1250 0 11 291 30

In order to obtain and determine the graphic and statistic data, the students used tools such as Excel, CurveExpert and CODAP.

Conclusions

1. The Erath’s albedo in the Eastern geographical area of ​​Spain is 28, although the average is 0.38. This difference between the data is due to the fact that there are many factors that influence this calculation  which may change the result, such as the type of surface when  the rays of the sun fall upon.
2. The maximum horizontal wind speed was 137 km/h during the descent at 13.255 m. The minimum speed was 2 km/h during the ascent at 18.768 m. The highest altitude is 455 m. The area where the wind currents most affect the probe is between 13.000 m and 15.000 m. In there ,the weather balloon reaches the maximum horizontal speed during the ascent  and the descent
3. The weather balloon rises up to an altitude of 455 m in a practically constant speed of 5 m/s. However, the speed in the descent is absolutely   constant   and it is of 7 m/s.
4. The probe begins to record data at 141 m. The internal temperature  is of 9 degrees and descends to 0 degrees when it  reaches  11.906 m. The temperature continues to decline below zero to 4.601 meters reaching -7 degrees. From this measure, the temperature rises again to 0 degrees and an altitude of 1.250 m.

At   14.013 m. the minimum external temperature is 49 degrees below zero.

The calculated value of the radius of the Earth is 1.175km .We compared our result with the real radius of the Earth (6371 km), and we  noticed that we  made a very big mistake. This may be due to the distortion of the image we had and the margin of error in our calculations.

Although the result was not what we expected, it is a very practical activity and gives the balloon probe a new utility.

The main benefits of undertaking such a project- based learning are:

• The students worked in groups in an autonomous and efficient way that helped to get group cohesion.
• The project allowed us to work with the PBL and STEAM methods.
• Students became more enthusiastic when tackling with Science and scientific vocations have been promoted thus.
• Coordination between different school departments (Science, Maths, Physics, English ) improved.

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