Meteorology Test 2

  1. Sketch and describe the movement of water through the hydrologic cycle.
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  2. The quantity of water lost to evaporation over the oceans is not equaled by precipitation. Why, then, does sea level not drop?
    The sea level doesn't drop because precipitation over land exceeds evaporation. Much of this precipitation returns to the oceans as run off in the hydrologic cycle.
  3. Name and describe the two processes that occur during evapotranspiration.
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  4. Water's solid phase, ice, is less dense than liquid water. Why is this unique property of water important?
    Ice being less dense than water is very important for aquatic life. Water freezes from the top down and the rate of freezing is slowed as the liquid below is insulated. This allows fish and other aquatic life to live through the winter.
  5. Explain what happens as ice melts to become liquid water.
    Hydrogen bonds are what hold the water molecules together to form ice through a hexagonal network. When ice melts, many of the hydrogen bonds break and the resulting water molecules form a compact arrangement which is why it is more dense than ice.
  6. What property of water causes large water bodies to remain warmer than adjacent landmasses in winter but cooler in summer?
    Water's heat capacity is what causes large water bodies to remain warmer in winter and cooler in summer, as the water heats up and cools down really slowly. This moderates the surrounding temperatures as the water remains warmer than adjacent land in winter and cooler in summer.
  7. Summarize the processes by which water changes from one state to another. Indicate whether heat is absorbed or liberated in each case.
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  8. Describe latent heat and explain the role that latent heat of condensation plays in the growth of towering clouds.
    Latent heat is the energy released or absorbed during a temperature process. This energy does not produce a temperature change. Latent heat is released when water vapor condenses to form cloud droplets. This warms the air creating buoyancy so when the moisture content is high, the growth of towering storm clouds can take place.
  9. Explain why evaporation is called a cooling process.
    Evaporation is the process of liquid converting to a gas (water vapor, for example). Energy is absorbed by water in order to give the molecules enough motion to escape the liquid surface. These fast moving molecules have a higher temperature and when they escape, the average molecular motion of the water is lowered therefore the temperature is lowered. This is why it is known as a cooling process.
  10. Why does the process of sublimation (or deposition) involve the exchange of more latent heat than any of the other processes that cause changes of state?
    Sublimation or deposition both require more latent heat than other processes that causes changes of state, because they essentially skip some of the processes. For example - sublimation is the conversion of a solid to a gas - essentially skipping the liquid state. This means it would require the total energy to convert from a solid to a liquid and then from a liquid to a gas, not just a little energy for one conversion at a time.
  11. How do absolute humidity and mixing ratio differ? What do they have in common?
    Absolute humidity is the mass of water vapor divided by the volume of air. Mixing ratio is the mass of water vapor divided by the mass of dry air. Mixing ratio looks at the mass of water vapor in a unit of air compared to the remaining dry air mass while absolute humidity looks at the mass of water vapor in a volume of air.
  12. Define vapor pressure and describe the relationship between vapor pressure and saturation.
    Vapor pressure the the part of the total atmospheric pressure attributable to its water-vapor content. Vapor pressure rises as saturation increases until a balance is reached.
  13. After reviewing Table 4-1 write a generalization relating air temperature and the amount of water vapor needed to saturate air.
    Lower temperatures require less water vapor to saturate the air. Higher temperatures require more water vapor to reach saturation.
  14. How is relative humidity different from absolute humidity and the mixing ratio?
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  15. Refer to figure 4-14 and then answer the following questions: A) When is relative humidity highest during a typical day? When is it lowest? B) At what time of the day would dew most likely form? C) Write a generalization relating changes in air temperature to changes in relative humidity.
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  16. If temperature remains unchanged, and if the mixing ratio decreases, how will relative humidity change?
    If the temperature stays the same, that means the amount of water needed to saturate the air will also remain the same. This value is in the denominator of the relative humidity ratio. So if the mixing ratio decreases, the relative humidity also decreases.
  17. List three ways relative humidity changes in value.
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  18. Define Dew-Point temperature.
    The dew-point temperature is the temperature that air must cool to in order to saturate.
  19. Which measure of humidity, relative humidity or dew point, best describes the actual quantity of water vapor in a mass of air?
    The dew-point temperature best describes the quantity of water vapor in an air mass.
  20. Describe the principle of a psychrometer, the tool used to measure relative humidity.
    A psychrometer has two thermometers mounted next to one another. One remains dry and measures air temperature while the other has a thin cloth wick that you saturate with water. The instrument is then swung around so a continuous air current passes over the wick and the water can evaporate from it and the wet bulb thermometer drops in temperature. The relative humidity and the dew point temperature can be determined through the use of a psychrometer.
  21. What does a chilled mirror hygrometer measure?
    A chilled mirror hygrometer measures the dew-point temperature of the air.
  22. What name is given to the process whereby the temperature of air changes without the addition or subtraction of heat?
    Adiabatic temperature changes
  23. Why does air expand as it moved upward through the atmosphere?
    As air moves up through the atmosphere, it moves through lower pressure and expends. It then cools adiabatically, as the molecules move less rapidly.
  24. At what rate does unsaturated air cool when it rises through the atmosphere?
    Unsaturated air cools at a constant rate of 10°C Every 1000 meters of ascent
  25. Why does the adiabatic rate of cooling change when condensation begins?
    Latent heat is released from the water vapor when condensation occurs, which causes the cooling rate to slow down in the saturated air.
  26. Why is the adiabatic rate not a constant figure?
    It varies because the amount of latent heat released also varies based on the amount of moisture present. The cooling rate is more rapid in areas of lower moisture content.
  27. The contents of an aerosol can are under very high pressure. When you push the nozzle on such a can, the spray feels cold. Explain.
    The contents are no longer under high pressure and expands as it leaves the can which allows it to cool.
  28. How do orographic lifting and frontal wedging act to force air to rise?
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  29. Explain why the great basin of the western United States is dry. What term is applied to such a situation?
    The Great Basin is a "rain shadow desert". Due to orographic lifting, air ascends a mountain and generates clouds and precipitation. When it reaches the leeward mountain side, most of the moisture has been lost. If it descends, precipitation is less likely as the air warms adiabatically leading to a rain shadow desert. This is why the Great Basin is so dry.
  30. Explain why Florida has abundant mid afternoon thunderstorms.
    Florida experiences airflow from the ocean which leads to a pileup of air by the coasts and convergence over its peninsula. Solar heating also contributes greatly to this uplift and air movement. This is why they experience a large frequency of midafternoon thunderstorms.
  31. Describe localized convective lifting.
    Localized convective lifting is the phenomenon that produces thermals. Thermals are pockets of warm air that form due to unequal heating of the Earth's surface. They rise due to being warmer than the surrounding air.
  32. How does the stable air differ from unstable air?
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  33. Explain the difference between the environmental lapse rate and adiabatic cooling.
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  34. How is the stability of air determined?
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  35. Write a statement relating the environmental lapse rate to stability.
    The environmental lapse rate is a measurement of the actual atmospheric temperature. Tracing a parcel's temperature compared to the environmental lapse rate can determine the stability of the air. If a hypothetical parcel rising would be cooler than the lapse rate, the air is stable. If the parcel is warmer, the air would be unstable.
  36. Describe conditional instability.
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  37. What weather conditions would lead you to believe that air is unstable?
    For unstable air, I would expect thick, tall clouds with heavy precipitation.
  38. What weather would conditions lead you to believe that air is stable?
    For stable air, I would expect either clear skies or very little clouds - and the clouds wouldn't be very thick. There could also be very light precipitation.
  39. List four ways instability can be enhanced.
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  40. List three ways stability can be enhanced.
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Card Set
Meteorology Test 2
Test 2