Can You Take the Pressure? Atmospheric Pressure: How and why it changes and how that affects the Human Body. A graph is a picture. A picture is worth a thousand words. One of the best ways to learn about atmospheric pressure on Earth is to create a graph that illustrates the relationship between air pressure and altitude. After you create one graph, you will label and illustrate another graph to tell a story about our Earth's atmosphere. By learning about atmospheric pressure, you will learn more about the atmospheric conditions on Space Station Alpha. First, you must learn several important scientific terms. Take time to read the article, "A Weighty Topic." [Writer's Note: Link here to A Weighty Topic] Don't forget, "mmHg" stands for millimeters of mercury, and STP stands for standard temperature and pressure, or 59( Fahrenheit and 760 mmHg. To create your graph, follow these instructions. As you proceed you will discover how air pressure changes with altitude. 1. Create a table with three columns. Column 1) Fact #. Column 2) The Altitude (000 Feet) Column 3) The Atmospheric Pressure (mmHg). The title of the Table is "Altitude and Atmospheric Pressure." Example: Fact # The Altitude (000 Feet) The Atmospheric Pressure (mmHg) 1. 0 760 2. 5 632 3. Etc. Complete this table using the facts in #2 below. 2. Use these FACTS to fill in the table. # At sea level, or 0" altitude, the atmospheric pressure = 760 mmHg at STP. At an altitude of 5,000", the atmospheric pressure = 632 mmHg. At an altitude of 6,288", the atmospheric pressure = 605 mmHg At an altitude of 10,000", the atmospheric pressure = 523 mmHg. At an altitude of 12,000", the atmospheric pressure = 485 mmHg. At an altitude of 15,000", the atmospheric pressure = 429 mmHg. At an altitude of 18,000", the atmospheric pressure = 50% of atmospheric pressure of sea level. (Calculate the atmospheric pressure.) At an altitude of 29,028", the atmospheric pressure = 215 mm Hg atmospheric pressure of sea level. At an altitude of 35,200", the atmospheric pressure is 25% of sea level. (Calculate the atmospheric pressure.) At an altitude of 40,000", the atmospheric pressure is 140 mmHg. At an altitude of 50,000" the atmospheric pressure is 87 mm Hg. At an altitude of 62,000", the atmospheric pressure = 51.71 mm Hg. At an altitude of 65,000", the atmospheric pressure = 45 mm Hg. At 110,000í altitude, the atmospheric pressure = 7.6 mm Hg. 3. On an 8.5 x 11" graph paper, draw an x and y-axis and label both as described. Title the graph, "Atmospheric Pressure Vs. Altitude." The x-axis, or the horizontal axis, should be the longest axis running along the 11" side of the paper. The x-axis will represent mmHg, or millimeters of Mercury. Place the graph paper with the 11" length across your desk. Starting three graph spaces in from the lower left hand corner and three spaces up from the bottom of the paper, draw the x-axis. Label it "Atmospheric Pressure (mm Hg)." Number the x-axis from 0 to 800 in increments of 50 (0, 50, 100, 150, etc. to 800). The x-axis represents atmospheric pressure from 0 mmHg to 800 mmHg. The y-axis, or the vertical axis, represents altitude in thousands of feet. Create the y-axis. Label it "Altitude (000 Feet)", and number it from 0 to 130 in increments of 10"(0, 10, 20, 30, etc. to 130). The three "0"'s in parentheses mean that every increment of 10 on your y-axis represents 10,000 feet. The y- axis represents the altitude from 0 feet, or sea level, to 130,000 feet, where there is virtually no air molecules left to create a measurable pressure. 4. Transfer the information from your Table (#1, above) to your graph. Use a Pencil! Record and connect the points that you have collected in your Table above on the graph. When you have plotted the points on your graph, connect them. The line through the points represents the relationship between atmospheric pressure and altitude. Remember, all these air pressure measurements might be different if we were not working at STP. It gets much colder that 59( Fahrenheit as we go higher in space. The air pressure inside a hurricane can drop as much as 50mmHg, or more. Your curve, however, gives you a good picture of how air pressure decreases as we increase altitude. This relationship is an excellent example of what scientists call an "inverse relationship," meaning when one variable increases, the other decreases. 5. Check your graphing skills. Get a pre-printed copy of the "Atmospheric Pressure vs. Altitude" graph called "Graph B." You will illustrate and label this pre-printed copy. Label your original copy "Graph A." Before you do anything else, compare the curve of the graph you made with the curve of Graph B. Are the altitude vs. air pressure curves the same? If so, you did a great job making your graph. If not, make the necessary adjustments to your original, Graph A. You will now label and illustrate Graph B. The curve tells us that as we go up in the air in airplanes, or balloons, for instance, the air pressure drops. There are fewer molecules of air. The number of molecules in the air and the air's pressure are directly related! This relationship is what scientists call a "direct relationship." Add a subtitle to Graph B, "Humans and Altitude on Earth." Use the facts below to label and illustrate your graph. The labels are in quotations marks. You are asked to fill in the air pressure by "reading" it off of the x-axis. If necessary, add a "point" to your Altitude vs. Pressure curve and then the label the point. [Authorís Note: Put one sample label on graph to show "best" approach to labeling.] 1. At 5,000": "Hypoxia #1, ___mmHg" (See Hypoxia) [Link] 2. At 6,288": "Mt. Washington, ___mmHg" The tallest mountain in the Northeast, US. Lightly draw the peak beneath the Altitude/Pressure curve. 3. At ??,???": "Mt. ______________ , ___mmHg" The tallest mountain in your state. Place a point on the Altitude/Pressure curve on your graph. Label the point. Lightly draw the peak beneath the Altitude/Pressure curve. 4. At 12,000": "Hypoxia #2, ___mmHg" (See Hypoxia Chart)" [Authorís Note: Link to Hypoxia Chart] 5. At 18,000": "Water boils at 180â, ___mmHg" At 20,320": "Mt. McKinley, ___mmHg" Tallest mountain in US. Lightly draw the peak beneath the line. Add the point to the Altitude/Pressure curve. 6. At 29,028": "Mt. Everest, ___mmHg" Tallest mountain in the world. Lightly draw the peak beneath the Altitude/Pressure curve. What is the atmospheric pressure at the top of Mt. Everest? 7. At 40,000": "Label: "Cannot breathe with gas masks, ___mmHg" 8. At 44,500": "Label: "Lungs Stop Working, ___mmHg" The body's diaphragm no longer has enough strength to expand to fill the lungs. 9. At 65,000": "Label: "Water boils at 98.6â, ___mmHg." If it weren't for the protective layer of skin on our bodies, the blood of anyone above this level would boil just from the temperature that our body creates. 10. At 222 mmHg: "Label: "Pressure in an EMU or Space Suit." Add this point to the curve. 6. Get a copy of the Atmospheric Pressure Vs. Altitude Graph C, subtitled "Astronauts on Space Station Alpha." •Study the labels. "Safe Outside Operating Pressure Range: 600mmHg ñ 860mmHg." • "Optimum Space Station Maintenance Range: 700mmHg ñ 770mmHg" • "Normal Astronaut Working Conditions: 718mmHg" • "Maximum Allowable Atmospheric Pressure: 786mmHgLabel:" • "Atmospheric Pressure in Space Suit": 222mmHg • "Warning Acute Hypoxia Possible: 540mmHg" You now have three Atmospheric Pressure vs. Altitude Graphs, A, B, and C. These three charts tell one story. The conclusion of the story is that the atmosphere in the Space Station has to be maintained so that conditions remain close to those the Astronauts are used to on Earth. If conditions change, their bodies will begin to show signs of illness. On Earth, we have learned through experimentation and tragedy how humans react to changes in atmospheric pressure. We know when the Astronaut's minds might show distinct disorientation due to Hypoxia, and when the pressure in the Space Station drops to the same pressure that we find at an altitude of 12,000 feet. At what altitude/pressure would the Astronauts be in danger of losing their night vision? In Space Station Alpha, a loss of air pressure for the Astronauts is the same as an increase in altitude is for us on Earth. On the Space Station the air pressure might drop if there were a leak, or if the ELCSS equipment malfunctioned. Could the air pressure in the Space Station ever drop as low as if the astronauts had climbed to the top of Mt. Everest? What air pressure would the astronauts experience under these conditions?