Development of a Simple PET (plyethylene terephthalate) Bottle Barometer and Meteorological Observation

Abstract

This study presents a new method of meteorological observation using a simple barometer made by inserting a straw into the cap of a PET bottle. The change in air pressure can be read by the shift of the water level in the straw. When the atmospheric pressure decreases/increases, the water level in the straw ascends/ descends. The shift of the water level in the PET bottle is slight in comparison with that in the straw. First of all, we observed the air pressure on each floor of school buildings. The results showed that the pressure differed on each floor, that the level was in proportion to the number of the floor, and that the average of pressure difference between the 4th and 1st floors was over 1hPa. Thus the change of air pressure can be easily seen in climbing/descending the stairs. The shift in the water level was theoretically discussed under an air pressure increase of 1hPa and no change of temperature. The results showed that the shift became visibly larger because of the small diameter of a straw tube, the large volume of air in the PET bottle, and the low density of liquid. We also conducted the experiment by using an elevator. These results agreed with the theoretical results roughly. This method of meteorological observation with a simple PET bottle barometer has been planned for use in a lower secondary school. The result in the trial lesson showed that many students observed the shift of the water level, that many students felt this activity interesting and this teaching material useful, and that this activity encouraged students to study the weather.