You already know that atmospheric pressure decreases as altitude increases simply because there are fewer and fewer air particles at higher elevations. But what is the exact relationship between atmospheric pressure and altitude? The data below represents average atmospheric pressure over a range of altitudes.
| Atmospheric Pressure (hPa/mb) | Altitude (km) |
| 1013.25 | 0.00 |
| 954.61 | 0.50 |
| 898.76 | 1.00 |
| 845.59 | 1.50 |
| 795.01 | 2.00 |
| 746.91 | 2.50 |
| 701.21 | 3.00 |
| 657.80 | 3.50 |
| 616.60 | 4.00 |
| 577.52 | 4.50 |
| 540.48 | 5.00 |
| 505.39 | 5.50 |
| 472.17 | 6.00 |
| 440.75 | 6.50 |
| 411.05 | 7.00 |
| 382.99 | 7.50 |
| 356.51 | 8.00 |
| 331.54 | 8.50 |
| 308.00 | 9.00 |
| 285.84 | 9.50 |
| 264.99 | 10.00 |
Plot a graph of Atmospheric Pressure vs. Altitude for this data. Draw a curve of best fit through your data points. Extrapolate your curve of best fit to an altitude of at least 14 km. (Hint: Atmospheric Pressure is your dependent variable, so it acts as your y coordinate. Altitude is your independent variable and is your x coordinate.)
| Location | Altitude (km) | Atmospheric Pressure (hPa/mb) |
| Calgary, Alberta | 1.1 | 889 |
| Albuquerque, New Mexico | 1.6 | 831 |
| Mt. Shasta, California (summit) | 4.3 | 585 |
| average cruising altitude of a commercial jet | 11.0 | 227 |
Note: Answers for the atmospheric pressure may vary slightly from the sample values given here because of accuracy in reading the graph. Values should, however, be fairly close to these.