Atmospheric or barometric pressure is the result of the weight of a column of air above a given location. The elements and compounds that comprise the atmosphere have mass, and therefore exert a force within a gravitational field, i.e. weight. The amount and density of the atmosphere will determine the atmospheric pressure. The greater the height of the column of air or the greater its density, the higher the pressure will be. Conversely, a short column of air or a lower density will result in lower pressure.

As you have learned in previous labs, we unfortunately live in a country which insists on using the outdated and inconsistent English system of measurements. To equate measurements of pressure in English to Metric units requires converting one unit to another.

1 in. Hg = 33.8639 mb 1 in. Hg = 25.4 mm Hg 1 mm Hg = 0.0393701 in. Hg 1 mm Hg = 1.33322 mb 1 mb = 0.02953 in. Hg 1 mb = 0.750062 mm Hg

Fill in the table below by converting the following English and Metric pressure units using the conversion formulas given below. Report all answers to 2 decimal places.

1. Complete the following table of barometric pressure conversions. Report all values to 2 decimal places. 1a. 19.63 inches of Hg = millimeters of Hg 1b. 25.57 inches of Hg = millimeters of Hg 1c. 30.01 inches of Hg = millibars 1d. 29.85 inches of Hg = millibars 1e. 550.00 millimeters of Hg = inches of Hg 1f. 725.25 millimeters of Hg = inches of Hg 1g. 789.50 millimeters of Hg = millibars 1h. 635.75 millimeters of Hg = millibars 1i. 985.00 millibars inches of Hg 1j. 972.00 millibars inches of Hg 1k. 1001.00 millibars millimeters of Hg 1l. 1015.00 millibars millimeters of Hg

2. Using the pressure-elevation equation from your lab manual and given the elevation (h), calculate the atmospheric pressure (P). Report all values to 2 decimal places. 2a. 350 m = millibars 2b. 785 m = millibars 2c. 1120 m = millibars 2d. 1560 m = millibars 2e. 2597 m = millibars 2f. 3001 m = millibars 2g. 4596 m = millibars 2h. 6500 m = millibars

3. On the linked map, draw the isobars for every 4 millibars of pressure starting at 1000 mb (1000 mb, 1004 mb, 1008 mb, 1012 mb, etc.). On the map, due to space imitations, only the last two digits of the millibar pressure has been indicated. For example, 1000 mb would appear as 00, 1020 mb would appear as 20, and 995 mb would appear as 95. Draw each isobar line to just past the edge of the continent.