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2011-01-25 18:40:11
Apologia General Science Module

Study for Section 3
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  1. Atmosphere
    The mass of air surrounding a planet
  2. Atmospheric pressure
    The pressure exerted by the atmosphere on all objects within it
  3. Barometer
    An instrument used to measure atmospheric pressure
  4. Homosphere
    The lower layer of earth’s atmosphere, which exists from ground level to roughly 80 kilometers (50 miles) above sea level
  5. Heterosphere
    The upper layer of earth’s atmosphere, which exists higher than roughly 80 kilometers (50 miles) above sea level
  6. Troposphere
    The region of the atmosphere that extends from ground level to roughly 11 kilometers (7 miles) above sea level
  7. Stratosphere
    The region of the atmosphere that spans altitudes of roughly 11 kilometers (7 miles) to 48 kilometers (30 miles)
  8. Mesosphere
    The region of the atmosphere that spans altitudes of roughly 48 kilometers (30 miles) to 80 kilometers (50 miles)
  9. Jet streams
    Narrow bands of high-speed winds that circle the earth, blowing from west to east
  10. Heat
    Energy that is transferred as a consequence of temperature differences
  11. Temperature
    A measure of the energy of random motion in a substance’s molecules
  12. Thermosphere
    The region of the atmosphere between altitudes of roughly 80 kilometers and 460 kilometers
  13. Thermosphere
    The region of the atmosphere between altitudes of roughly 80 kilometers (50 miles) and 460 kilometers (285 miles)
  14. Exosphere
    The region of the atmosphere above an altitude of roughly 460 kilometers (285 miles)
  15. Ionosphere
    The region of the atmosphere between the altitudes of roughly 65 kilometers (40 miles) and 330 kilometers (205 miles), where the gases are ionized
  16. Suppose the earth’s atmosphere contained twice the number of molecules it does today. Would atmospheric pressure be greater than, equal to, or less than it is now?
    • Atmospheric pressure would be greater than it is now.
    • After all, if there were twice as many molecules in the air, the mass of air pressing down on everything in the atmosphere would be twice as high.
  17. Two students make two different barometers. Although they are placed side by side so that they are both exposed to exactly the same atmospheric pressure, the column of liquid in the first student’s barometer is significantly lower than the column of water in the second student’s barometer.
    Assuming both students made their barometers correctly, what explains the difference?
    • The students used different liquids.
    • A given volume of the liquid used by the first student weighs more than the same volume of the liquid used by the second student. Remember how a barometer
    • works. The height of the column of liquid is determined by the amount of liquid ecessary to counteract the atmospheric ressure pushing on the liquid. The heavier the liquid, the less will be necessary to achieve this effect. Thus, if a given volume of liquid used by the first student weighs more than the same volume of liquid used by the second student, the liquid in the first student’s
    • barometer will not have to rise as high to counteract the force provided by atmospheric pressure.
  18. What is atmospheric pressure at sea level?
    • 14.7 psi (pounds per square inch)
    • or
    • 29.9 inches of mercury
  19. The average, sea-level value for atmospheric pressure is 14.7 pounds per square inch, which is the same as 29.9 inches of mercury. If the atmospheric pressure is 0.85 atms, which of the following values would correspond to atmospheric pressure as reported in a weather report?

    31.1 inches of mercury, 29.9 inches of mercury, 25.4 inches of mercury
    • An atmospheric pressure of 25.4 inches of mercury would be reported.
    • Since 1.0 atm corresponds to the average sea-level value of atmospheric pressure, 0.85 atms means that the atmospheric pressure is lower than average.

    • 29.90
    • x .85
    • 25.4640
  20. Two vials contain air samples taken at different altitudes. The first is composed of 21% oxygen, 78% nitrogen, and 1% other. The second is 95% helium, 4% hydrogen, and 1% other. Which came
    from the homosphere?
    • The first came from the homosphere.
    • In the homosphere, the mixture of gases in the air is the same throughout. It is the mixture we learned in the previous module. The heterosphere has many different compositions, depending on altitude.
  21. You are reading the data coming from a data-gathering balloon as it rises in the atmosphere. You have no idea what altitude it is at, but the balloon is sending a signal from its thermometer, telling you the temperature of its surroundings. How will you know when the balloon enters the stratosphere?
    How will you know when it enters the mesosphere?
    • The balloon enters the stratosphere when its temperature readings cease to decrease and begin increasing. The balloon enters the mesosphere when the temperature readings cease increasing and begin decreasing again.
    • Since the temperature gradient changes at the stratosphere and then again at
    • the mesosphere, this can be used to determine when the balloon has reached those parts of the atmosphere.
  22. Name the three regions of the homosphere, from lowest to highest.
    • Troposphere [sea level to 11k (7 mi)],
    • Stratosphere [11k (7 mi) to 48k (30 mi)],
    • Mesosphere [48k (30 mi) to 80k (50 mi)
  23. Although the temperature gradient changes from region to region in the homosphere, there is one gradient that stays the same. It continues to decrease as you increase in altitude, no matter where you are in the homosphere. To what gradient am I referring?
    I am referring to the “amount gradient.” You could also answer with “pressure gradient.” Both the amount of air and the pressure decrease with increasing altitude. Remember, “gradient” just means steady change, so I can use that term with any quantity.
  24. A plane is experiencing a lot of problems because of a storm in the area. Is the plane flying in the troposphere or the stratosphere?
    The plane is flying in the troposphere. That’s where the majority of weather phenomena exist.
  25. A scientist has two vials of ammonia gas. She tells you that in the first vial, the gas molecules are traveling with an average speed of 1,000 miles per hour. In the second vial, they are traveling with an
    average speed of 1,300 miles per hour. Which vial contains the gas with the higher temperature?
    • The second vial contains the gas with the highest temperature. Remember, temperature is a measure of the energy of random motion in a substance. Since the molecules in the second vial have a
    • higher speed, they have more energy and thus a higher temperature.
  26. As you are outside on a cold winter night, you begin to shiver from the cold. Your companion says that you are shivering from the heat. Is your companion correct? Why or why not?
    Your companion is correct. Heat is energy that is being transferred. The reason you are cold is that energy is being transferred from your body to the surrounding air. Even though it sounds weird to say it, you get cold because of transferred energy; thus, you get cold because of heat!
  27. Suppose there were a layer of carbon dioxide gas in the mesosphere. What would happen to the temperature gradient in that region?
    The temperature gradient would reverse, getting warmer near that region. Remember, the temperature increases with increasing altitude in the stratosphere because of a layer of the greenhouse gas ozone. Carbon dioxide is also a greenhouse gas, and thus would produce roughly the same effect.
  28. Why will the ban on CFCs most likely not save or improve people’s lives?
    A ban on CFCs will probably not save or improve lives because CFCs cause a depletion of ozone only during a few months out of the year and mostly over Antarctica. Since there is no significant population there, and since the depletion is temporary, the “ozone hole” is not a big threat to human survival.
  29. Why will the ban on CFCs most likely result in a tragic loss of human life?
    A ban on CFCs will most likely cost many lives because refrigeration, surgical sterilization, and firefighting will all be less efficient, causing death by starvation, death by eating food-borne illness, death by surgical infection, and death by fire.
  30. Even though human civilization is responsible for less than 1% of all chlorine in the atmosphere, it is responsible for 80% of all ozone-destroying chlorine. Why?
    Some kinds of human-made molecules that contain chlorine can survive the trip up to the ozone layer, while most naturally produced chlorine-containing molecules cannot. Thus, although we produce few chlorine-containing molecules, many of them can reach the ozone layer, where ozone depletion can occur. As a result, most of the ozone-destroying molecules in the ozone layer are from human sources.
  31. What makes it possible for CFCs to travel up to the ozone layer and begin destroying ozone?
    The polar vortex lifts the CFCs into the ozone layer. Since the polar vortex is seasonal and limited mostly to the South Pole, so is ozone depletion.
  32. Where is the ionosphere, and what makes it useful to us?
    The ionosphere is a stretch of the atmosphere ranging from the upper mesosphere to the lower parts of the thermosphere. It is useful to us in radio communication, as radio signals can bounce off of it to extend their range. An altitude range of roughly 65 km to 330 km is also a valid answer to where the ionosphere is.