EAS 100-51: Introduction to Earth Science

Note: These essay-style questions are a supplement to (NOT a subtitute for) lecture notes, handouts, and text reading

1. a. pelagic, b. benthic, c. abyssal, d. hadal

2. Deep-sea creatures, in general, are:

a. small, because there is not as much food in deep waters

b. usually red or black in color, since there is not much light

c. internally-pressurized to equalize the pressure of deep water (when caught by fisherman, they explode)

d. they usually have large mouths; long, sharp teeth, and some have "fishing lures" which glow in the dark. Examples: the deep-sea gulper can swallow animals as large as themselves, and the deep-sea angler dangles its "lure" in front of its huge mouth to attract prey

3. Giant squids, 35 to 50 feet long, have been found as carcasses at the ocean surface, so they do indeed exist. The largest confirmed size for an octopus is about 30 feet long, although the arms of a huge octopus had reputedly been found (the evidence was destroyed, however) suggesting that it was 100 feet long!

4. The sperm whale (of "Moby Dick" fame) takes a deep breath and dives down to 5000 feet to hunt for giant squid. The whale can hold its breath for an hour, while it does battle. Since this whale has teeth, it eventually kills the squid by biting off the arms and tentacles and eating the squid. Scars from these epic battles have been seen on whales.  (It is also possible that an especially large and strong giant squid could have occasionally defeated a sperm whale, but we'll never know for sure.)

5. At the equator, there is more rainfall (freshwater), so ocean water is diluted and not as salty. At the mid-latitudes, there is more evaporation from the ocean, so the water becomes saltier.

6. In general, colder ocean water supports more dissolved oxygen than does warner ocean water, and thus more dissolved chemical and biological nutrients, which is favorable to plankton (tiny algae and shrimp-like creatures which form the basis of the marine food chain). Warm water regions such as the equator are "oceanic deserts" as far as the abundance of ocean life is concerned, because oxygen gas molecules vibrate more quickly and are more likely to escape from warm oceans.

7. The continental shelf is the extension of the continental land mass; it is a wedge of eroded sediments transported by streams.

8. Origin of Earth's Water: During the first 800 million years of the Earth's earliest history, catastrophic bombardment by asteroids, meteorites, and comets (composed mostly of ice and dust) caused the earth's original crust to re-melt repeatedly.  The intense volcanism induced by this extraterrestrial bombardment also brought water trapped in the magma of the earth's mantle up to the surface.  Eventually, meteorite bombardment slowed down, the crust stabilized, and the earth's surface temperature cooled enough for the steam to condense into liquid water and fall as rain. It may have rained for centuries in order to fill the ocean basins.

9. Massive sulfides are metallic ore minerals containing the element sulfur (examples: pyrite, chalcopyrite, sphalerite, etc.). Massive sulfides are usually found on land, but have recently been discovered along mid-ocean ridges; they are precipitated into the ocean water as dark clouds (called "smokers"). Strange creatures living in these waters are able to use the sulfides as a food source (with the help of special microbes), and the volcanic heat to survive.

10. Manganese nodules are round or oval rocks containing manganese oxides. They are found in great abundance on the ocean floor, and are believed to be the work of microbes. At some time in the future, they may become a future source of ore minerals, since manganese is widely used in steel-making.

11. The Coriolis Effect is an apparent change noted in the movement of an airborne object, caused by the Earth's rotation. In essence, the rotating Earth changes its relative location while the object is moving through the air (thus "unattached" to the ground); this effect was responsible for causing long-range artillery shells to miss their targets during World War I. The Coriolis Effect causes counterclockwise circulation of ocean currents in the Northern hemisphere and clockwise circulation in the Southern hemisphere.

12. Ocean waves are generated by winds at the surface of the waters.  Dye testing in wave tanks have proven that waves are actually a change in shape of the water by energy waves passing through, NOT the movement of the water molecules themselves.   The water molecules actually follow small, circular paths that decrease in radius with depth; below a depth equal to half the wavelength, there is effectively no water movement (this depth is called the wave base).

13. Weather is the short-term description for atmospheric conditions, usually measured over hours, days, or weeks. Climate is a long-term composite or average of the weather over a much longer period, usually decades or centuries.

14. Four elements or variables of weather: heat, pressure, wind, & moisture

15. The present atmosphere is composed of: Nitrogen (78%), Oxygen (21%), with the remaining one percent a mixture of argon, carbon dioxide, water vapor, and other gases.

16. Carbon dioxide makes up only 0.03% of the gases which make up clean, dry air. It acts as a "greenhouse gas" which permits incoming short-wave radiation from the sun, but prevents the long-wave radiation of the earth from going back into space. The CO2 absorbs some of the energy leaving the ground, warming the air near the ground.

17. Nitrogen and oxygen normally exist as diatomic molecules (pairs of atoms - N2 and O2. In this form, N2 cannot be utilized by plants as a nutrient because it does not dissolve in water; it has to be broken down into nitrate, which is -NO3 and dissolves easily in water. The very strong triple bond which holds nitrogen atoms together may be broken by the tremendous energy of lightning in common rainstorms.

18. Ozone is triatomic oxygen (O3) which is made in the upper stratosphere by intense ultraviolet radiation from the sun. The energy bombardment in this zone breaks apart many O2 molecules into single O atoms which bond with regular O2 molecules to form O3. Ozone is a good filter for ultraviolet radiation, so it protects life down on the earth's surface.

19. Earth's early atmosphere was probably made up largely of ammonia (NH3), methane (CH4), carbon dioxide (CO2), and water vapor.  There was no free oxygen in this early atmosphere.

20. Most early life forms lived in the oceans, since there was no ozone layer yet, and the sun's ultraviolet radiation bombarding the land was much too strong to support life. The first life forms did not require oxygen - they were anaerobic. After the first plants evolved, a by-product of their life cycle was oxygen. The successful spread of plants on the early earth transformed the atmosphere about 1 billion years ago from an anaerobic (lacking in oxygen) to aerobic (abundant free oxygen) environment. The presence of this abundant oxygen allowed the ozone layer to form, eventually making life on land possible.

21. The distances of the planets from the sun determined how much heat each planet received; only Venus and Earth are close enough the have abundant liquid water. The size of each planet determined the individual mass and gravitational pull; large planets have thicker atmospheres richer in gases such as hydrogen.

22. Venus is a special case of a "runaway greenhouse effect" caused by the trapping of solar heat by its heavy carbon dioxide atmosphere; Venus is much hotter than it should be, as a result; hot enough to melt lead, and with surface pressures equal to 90 atmospheres.

23. Two ways to increase atmospheric pressure:
a) increase the number of collisions between gas molecules - cause them to vibrate more quickly by adding heat energy
b) increase the number of collisions by increasing the number of gas molecules.

24. Air is thinner at higher altitudes because the gas molecules are further apart from each other; at greater distances from the center of the Earth's gravity, gas molecules have greater freedom of movement.

25. We are able to distinguish that part of the electromagnetic spectrum called visible light. Red-Orange-Yellow-Green-Blue-Indigo-Violet (ROYGBIV)

26. Conduction is a method of heat transfer involving the direct collision of molecules; it requires direct contact between a hot object and a cooler one. Convection is a method of heat transfer which involves the movement or circulation of a liquid or gas.

27. Albedo is a measure of the earth's ability to reflect sunlight. 100% albedo = total reflection. 0% albedo = total absorption. Light-colored objects (such as fresh snow) have a high albedo, dark-colored objects (such as Illinois soil) have a low albedo.

28. Greenhouse warming is accomplished by the atmospheric gases carbon dioxide and water vapor. These gases permit short-wavelength radiation from the sun to penetrate to the surface where refraction and reflection causes some of the sunligght to change to longer wavelengths; the earth attempts to reflect longer wavelength radiation back into space, but the greenhouse gases trap this radiation, warming the air near the ground. Without these greenhouse gases, the climate of the earth would be cooler than it is.

29. Relative humidity is the amount of the moisture in the air, measured against the maximum capacity of that air to hold moisture. This moisture holding capacity (called the saturation point) varies with temperature.   Warmer air has a higher capacity to hold water vapor than colder air.

30. Fair weather is associated with descending air and diverging winds (see Figure 14.9, page 390).

Storm Type:
hundreds of miles wide usually less than a quarter mile wide
born in the tropical oceans born on land (most often in midwestern U.S.)
75 mph or greater wind speed can sometimes exceed 200 mph or greater wind speed
several days to over a week several minutes (less than 1 hr)
weakens as its moves from sea to the land weakens as it moves from the sea to the land land to water (waterspout)
path may be predicted path is unpredictable 

32. Lightning is generated when a cloud generates a high enough negative charge potential (due to excess electrons) to attract an object on the ground (positive charge). Lightning actually moves from the ground up to the cloud, or vice versa in a series of exchanges.

33. Peak tornado season, statistically-speaking, is during the month of May. April through June have the highest number of tornadoes.  The United States has the world's greatest occurrence of tornadoes, stretching from the Great Plains to the Midwest down through Florida ("Tornado Alley").

34 & 35. The large-scale burning of fossil fuels (oil, gas, and coal) increases the emission of carbon dioxide gas into the atmosphere, at a rate much faster than the natural carbon dioxide "sinks" (water bodies, trees, etc.) can absorb them. This increase in carbon dioxide is believed to make the greenhouse effect more pronounced, causing global warming over time.

36. Automobile exhaust emits sulfur dioxide (SO2), which mixes with oxygen to form sulfur trioxide (SO3). SO3 mixed with water (H2O) forms sulfuric acid (H2SO4), a corrosive acid. Rain in polluted urban areas carries dissolved sulfur dioxide which turns into acid rain.

37. CFC is an abbreviation of "chlorofluorocarbon," a family of gaseous organic compound containing carbon, chlorine, and fluorine. These man-made compounds were widely used as solvents and refrigerants. When disposed of, the CFC's escape to the upper atmosphere, where sunlight breaks them down, releasing chemically active chlorine and fluorine molecules that break down ozone into oxygen.

38. Other sources of additional atmospheric carbon dioxide (natural, not man-made): volcanic eruptions and insects (termites, ants, etc.).

39. The "hole" in the ozone layer was detected over Antarctica several years ago by scientists. It was attributed to the increase in CFC's in the upper atmosphere which had chemically destroyed part of the ozone layer. Because of these scientific findings, a majority of the world's nations have agreed to voluntarily phase out the production of CFC's in favor of substitute chemicals which do not harm the ozone layer.

40. The normal pH of rain water is slightly acidic (about 6.7 to 6.9) due to mixing with atmospheric carbon dioxide, forming weak carbonic acid. However, acid rain is caused by the mixture of rain water with sulfur dioxide from the combustion of fossil fuels, which yields sulfuric acid, a much stronger acid with a much lower pH (down to about 1.0).

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Copyright (c) 1994 by William K. Tong