GLOBAL CHANGE: GEOL 1060 An Earth Science Perspective Fall 2002 MidTerm Name ______________________________ Student Number ______________________ Carefully read each question; be certain you know what is being asked. True/False (Please spell out) 1) _______ 2 pts each The Pacific Ocean is on average saltier than the Atlantic Ocean. 2) ________ Deserts occur at the equator because that's where the greatest amount of solar radiation is received. 3) ________ Over 75% of the world’s fresh water is stored in groundwater. 4) ________ Surface currents in the ocean move on average about 90 degrees off the prevailing wind direction. 5) ________ Earthquakes and volcanos have the same primary forcing. 6) ________ Nitrogen is an important greenhouse gas in Earth’s atmosphere 7) ________ The boundary between the stratosphere and the troposphere is called the tropopause. 8) ________ Relative humidity is nearly constant across the globe. 9) ________ The latent heat of condensation is greater than the latent heat of freezing. 10) ________ Solar radiation is concentrated at shorter wavelengths than is radiation emitted from Earth. 11) ________ Thermohaline circulation is restricted to the Atlantic Ocean 12) ________ Summer in the Northern Hemisphere occurs when Earth is closest to the Sun. 13) ________ Hot spots are always associated with fluid volcanism. 14) ________ Almost all of the solar radiation that reaches the top of Earth’s atmosphere makes it through the atmosphere to the surface of the Earth. 15) _________ During a magnetic reversal, the Earth’s spin slows down then reverses the direction of spin, causing the magnetic field to change its orientation. 16) ________ Typical plate movements are roughly 5 to 10 kilometers per year. 17) ________ Because gases can be selective absorbers, they are all greenhouse gases. 18) ________ There was a very large greenhouse effect in Earth’s atmosphere even before human activity introduced large amounts of greenhouse gases to the atmosphere. 19) ________ Volcanism commonly occurs along transform plate margins. Multiple choice Select the BEST answer to each question 3 pts each 20) Stripes of rocks with alternating normal and reversed orientation of their magnetic minerals found on either side of the Mid-Alantic Ridge are evidence for: a) subduction b) downwelling c) feedback d) sea-floor spreading e) transpiration 21) Primary productivity is the fixation of inorganic carbon from the medium in which an organism lives (atmosphere, ocean, etc.) into organic carbon. The process by which they do this is called: a) transpiration b) photosynthesis c) downwelling d) emission e) homeostasis 22.) A seasonal reversal of the prevailing winds is known as a) Hadley Cell b) Monsoon c) Ferrel Cell d) Convection e) Coriolis Effect 23) New oceanic crust is formed along a) mid-ocean ridge b) subduction zones c) transform plate margins d) faults e) convergence zones 24) The primary forcing for plate tectonics is: a) b) c) d) e) Coriolis Effect Ekman Spiral The rotation of the Earth Gravity Radioactive decay deep in Earth’s interior 25) The natural greenhouse effect is caused by: a) Reflection of the sun’s radiation by clouds b) Changes in albedo causing positive feedback c) Gases in the atmosphere absorbing long wave radiation from Earth d) Changes in the climate in the last 4000 years e) Differential heating of the oceans and continents. 26) A phenomenon that causes moving objects in the northern hemisphere to veer to the right is: a) Republican Party b) Democratic Party c) Coriolis Effect d) Elvis e) Dr. Spock 27) You are skiing in the same area of the backcountry every weekend for many weeks during a snowy winter. Each time you cross a particular treeless slope you notice that the snow depth has increased from the previous trip. One snowy day, as you are skiing toward the slope, it slides away as an avalanche just before you arrive. This is an example of: a) random changes in nature b) positive feedback c) negative feedback d) threshold e) homeostasis 28) Which of the following is not true about hurricanes? a) b) c) d) e) They commonly originate at the equator. They originate in areas of warm surface waters (usually above 26 °C) They usually begin as a low pressure system Wind speeds increase in part due to the release of latent heat high in the rising air column They require the air to rotate 29) Which of the following does not occur at subduction zones? a) Oceanic crust is created b) Earthquakes c) Volcanism d) Oceanic crust is reincorporated back into the mantle Short Answer Questions want to know why. Keep the answers short, but do make them complete. In most cases, we 5 pts each 31) Sea-floor spreading occurs at a constant rate. On the ocean floor, alternating stripes of normal and reversed polarity on either side of the spreading center are not all of equal width (see figure above). What does this tell you about the length of time the Earth spends in periods of normal and reversed polarity? Justify your answer. 32) You are thinking of taking a vacation to Hawaii, but you hear on the news that Mauna Loa, the large volcano on Hawaii, is expected to have a major eruption at about the same time as you plan to arrive for your vacation. Would you change your plans? Justify your answer. sinking sinking upwelling upwelling warm surface current cold deep current The figure above shows oceanic thermohaline circulation. Answer the following questions. 33) Sinking of surface waters occurs in the northernmost North Atlantic. What are the two 3 pt mechanisms that cause the surface waters to increase in density in this area sufficiently that they sink? 34) The average residence time of a water molecule in the deepwater of the thermohaline pt circulation (the time between initial sinking and upwelling) is about : a) b) c) d) e) a few years a few hundred years a few thousand years tens of thousands of years millions of years 3