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Published byJulianna Osborne Modified over 9 years ago
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Bell Question: Using the captions to help you, explain why one of these containers was deformed. Picture 1: The Pringles can I packed from home is bulging. (In Yellowstone National Park, Elevation = ~9,000ft.) Picture 2: The bottle I left in the car is crushed. (At airport, Elevation = 0ft, coming home from Sequoia National Park, Elevation = ~7500ft)
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What is pressure? Amount of force in a given area – Particles push against each other to create a force Atmospheric Pressure = Weight of air as it pushes down on Earth’s surface (density) Atmospheric gases held in place by gravity
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Why isn’t air pressure the same everywhere? Pressure increases as you move deeper into the air Deepest point = EARTH’S SURFACE!!
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How do we measure pressure? A barometer measures inches of mercury or millibars A standard mercury barometer has a glass column about 30 inches long, closed at one end, with a mercury-filled reservoir. High atmospheric pressure forces the mercury higher in the column because of the weight of the air outside. Low pressure allows the mercury to drop to a lower level inside the column.
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30.65 Each notch is worth 1.0 1037.0 1038.0 1039.0 Each notch is worth 0.01 Page 13 of ESRT!
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Air pressure is NOT the same everywhere on Earth On Mount Everest: Pressure = 300mb At Sea Level: Pressure = _____ mb = ________ in (ESRT pg 13!) Tremendous Pressure Give it a try! 29 in = _____ mb 988 mb = _____ in 1013.329.92 982.029.17 29.18
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Why don’t we feel atmospheric pressure? –Fluids inside our bodies exert same pressure as atmosphere –Example: Travel from high to low elevation, ears “pop” * small pockets of air behind eardrums contract and expand to adjust to pressure*
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Relationships As altitude increases, pressure decreases (inverse) As temperature increases, pressure decreases (inverse) As humidity increases, pressure decreases (inverse) Altitude Temperature Humidity Pressure
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Why does pressure decrease with humidity? Water vapor is LIGHT compared to dry air Water Molecule –2 Hydrogens (Atomic Weight = 1) –1 Oxygen (Atomic Weight = 16) –Total Weight = 18 Dry Air Molecules –2 Nitrogens (Atomic Weight = 14) Total Weight = 28 –2 Oxygens (Atomic Weight = 16) Total Weight = 32
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30.71 28.73 29.92 29.53 29.915 1033.0 1016.0 995.5 972.0 992.2 At what altitude do you most commonly experience one atmosphere of pressure? Sea Level
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