Temperature Measurement Experiment
during the June 21, 2001 Total Solar Eclipse

Northern Zimbabwe
June 21, 2001

According to the GPS, the observing site was:
16° 24.842' S Lat.
31° 01.247' E Long.
Altitude: 477m





Finding some relief in the shaded area at the eclipse viewing site.
The temperature experiment was mounted on the back of the second post from the left.
I am standing in the shade just to the left of the post.






Overview of temperature experiment.
Alan Dyer of Calgary is the photographer on the upper right.






Upper portion of the experiment showing the 150cm level iButton ("A").






Lower portion of the experiment showing the 30cm level iButton ("D"), the 0cm level iButton ("C") and the buried dial thermometer.






Summary of Temperature Experiment Data




  • Results and Conclusions:
    1. All iButtons indicated a temperature drop starting about 37 minutes after First Contact while the buried dial thermometer didn't show a drop until at least 50 minutes after First Contact.
      1. The 150cm level showed a total drop of about 4°C.
      2. The 30cm level showed a total drop of about 7°C.
      3. The 0cm level showed an initial drop of about 7°C, levelled, then dropped an additonal 3°C for a total drop of 10°C.
      4. The buried dial thermometer showed a total drop of about 2°C.
    2. The measured temperatures were lower as the height above the ground increased.
    3. The temperatures measured with the dial thermometer (approximate average depth of 5cm) were similar to the 0cm iButton until the temperature drops started.
    4. All iButton-recorded temperatures began to increase at about 22minutes after Third Contact.
    5. The pause in the temperature drop of the 0cm level iButton shortly after Totality is not readily explained.
    6. The experiment had to be terminated before Fourth Contact because sunset was approaching and we wished to limit the time on the road after dark during the return to Harare.
    7. The overall conclusions regarding iButton use were:
      1. They provided useful temperature measurement information even though limited to 0.5°C and 1 minute interval accuracy.
      2. The iButton portion of the experiment was easy to set up and provided hands-free data collection.
      3. The dial thermometer proved very inconvenient to read, particularly during totality when so much is going on.
      4. Immersion in ice or rubbing proved adequate for time calibrating the iButtons around the eclipse period.
      5. Pre-calibration of the measured temperatures is required for accurate results. (eg. The "C" iButton used for the 0cm level measurements, routinely gave values of approximately 0.5°C lower than the other two iButtons and the control themometers, so a 0.5°C correction factor was added to all recored "C" iButton values)..



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