Temperature Correction for Mercury Barometers
The mercury in the barometer expands as the
temperature increases. The barometer is calibrated for 0oC. For higher
temperatures a correction must be applied to compensate for the
expansion of the mercury. The following table shows the
correction, in millimetres (mm), that should be subtracted from the reading of
atmospheric pressure. For observed heights of the mercury column between the listed values, you may
interpolate to determine the required correction.
| Temperature (oC) |
Observed Height (mm)
|
| 17 |
| 18 |
| 19 |
| 20 |
| 21 |
| 22 |
| 23 |
| 24 |
| 25 |
|
| 2.05 |
2.08 |
2.10 |
2.13 |
2.16 |
2.19 |
| 2.17 |
2.20 |
2.23 |
2.26 |
2.29 |
2.32 |
| 2.29 |
2.32 |
2.35 |
2.38 |
2.41 |
2.44 |
| 2.41 |
2.44 |
2.47 |
2.51 |
2.54 |
2.57 |
| 2.53 |
2.56 |
2.60 |
2.63 |
2.67 |
2.70 |
| 2.65 |
2.69 |
2.72 |
2.76 |
2.79 |
2.83 |
| 2.77 |
2.81 |
2.84 |
2.88 |
2.92 |
2.96 |
| 2.89 |
2.93 |
2.97 |
3.01 |
3.05 |
3.08 |
| 3.01 |
3.05 |
3.09 |
3.13 |
3.17 |
3.21 |
|
The above text and table are by David M. Harrison of the Department of Physics at the University of Toronto.