Earth Sciences Study Guide: Atmospheres

1. From Figure 4.2, describe the geographic locations where coastal upwelling is important (e.g., “west central and southwestern South America”).

Upwelling causes some of the coldest surface temperatures on Earth. The low surface temperatures stabilize the overlying atmosphere, causing cool dry climates (deserts) to dominate the western edge of South America. Upwelling is important where coastlines are left of the direction of flow in the northern hemisphere (North America, western coasts of parts of South America and Africa) and right of the flow in the southern hemisphere (eastern coasts of parts of South America and Africa).

2. From Figure 4.7, describe the geographic latitudes (to the nearest 15°) that are important source areas for deep ocean currents occur.

North Atlantic: near Iceland (65°N); South Atlantic: near Antarctica and the area east of the southern tip of South America (60°S); North Pacific: Aleutian Islands (35°N); South Pacific: near 65° S latitude          

3. Which gas emitted by volcanoes produces the most significant climatic signal?

            SO₂ – sulfur dioxide 

4. From Table 4.2, during El Niño events, which locations are drier than normal?

            Maritime Continent, southeastern Africa and Madagascar, east central Africa,

eastern South America (Brazil).

5. The Southern Oscillation Index is derived from sea level pressure differences between what oceanic regions?

            eastern and western Pacific (Darwin, Australia and Tahiti)

6. From Table 4.1, what provides indirect historical evidence for the existence of El Niño?

            variations in travel times from sailing vessels; ship logs noting unusual weather and

sea conditions; presence of “aguale” or red tide, a bloom of toxic maritime

plankton; abnormally warm waters along the South American coast; severe and unusual

weather events, such as heavy rains and flooding; property damage caused by floods;

travel obstructions from washed-out roads or mudslides; agricultural destruction;

increases in sea levels along the South American coast; mass mortality of marine sea life

caused by a decrease in the upwelling of nutrients; death and/or departure of birds;

reductions in productivity in coastal fisheries

 

7. What is the basis for the Walker circulation?        

            It describes the connection between the atmospheric pressure centers in the

equatorial Pacific, associated with the Southern Oscillation, the SSTs, and the

tropical trade winds that blow from east to west near the surface across the Pacific

Ocean (and other regions of the Earth within the tropics). It exists to balance the

normally observed pressure gradients over the tropical Pacific Ocean.

8. What does the Dust Veil Index estimate?

            the total amount of particulates in the atmosphere

9. A Volcanic Explosivity Index greater than what value is assumed to produce stratospheric emissions?

            4

10. What are the climatic impacts of large-scale deforestation?          

local temperatures will increase abruptly due to reduced shade, precipitation will decrease due to increased runoff and decreased transpiration, increased CO₂ concentrations in the atmosphere due to the reduction of the carbon sink and burning of the trees, reduced oxygen in the atmosphere due to the reduction in photosynthesis from removed trees,

increased CO₂ and CH₄ concentrations (acceleration of global warming) due to the deforestation of boreal forests

11. What are the causes of human-induced desertification?

            ranching and overuse of water

12. From Table 4.2, during El Niño events, which locations are warmer than normal?

            Japan, eastern Asia (China/Manchuria); northwestern North America (southern

Alaska through U.S. Pacific Northwest into central North America); eastern Canada

(Labrador, Nova Scotia)

13. What is the sequence of event that occurs during a La Niña?

During the La Nina phase, the trade wind flow along the equatorial Pacific Ocean becomes even stronger than normal, which increases warm water accumulation in the western equatorial Pacific and cold water upwelling in the east. This causes a deeper thermocline in the western tropical Pacific and a shallower than normal thermocline in the east. Sea levels respond accordingly, as the west records higher than normal sea levels and temperatures, while in the east lower than normal sea levels and temperatures occur.

14. What is the notion that increased warming will cause more phytoplankton growth, thereby increasing dimethyl sulfide and sulfur dioxide concentrations, condensation, and cloud cover known as?

            CLAW hypothesis

15. As what do proponents of the anti-CLAW hypothesis argue that warming of the ocean acts?

surface warming would increase the stable stratification within the ocean, with even warmer water overlying the cold bottom waters; increased stability would reduce the upwelling necessary to restore nutrients to the surface from depths; phytoplankton population growth would curtail due to the lack of nutrients; DMS production and transfer would decrease; less cloud cover would result, and amplification of the warming would occur

16. What causes gyres to form?

the coupling of the atmospheric and surface oceanic circulation around a subtropical anticyclone

17. Does a stable atmosphere enhance or inhibit vertical motions?

            inhibited

18. Is the California current a warm or a cold ocean current?

            cold

19. Are trade winds very weak or strong during a La Niña event?

            stronger than normal

20. Is global warming likely or unlikely to cause future changes in the hydrosphere?

            likely

21. What is the term for horizontal movement of air or water?

            (mass) advection

22. When marine evaporation is high and continental stream inputs are minimal, do ocean waters become more or less saline?

            more saline (dense, salty waters)

23. Do upwellings occur when offshore winds are parallel or perpendicular to a coastline and when net water advection near the surface is directed toward or away from the coastline?

            parallel to a coastline, when net water advection near the surface is directed away

from the coastline

24. Is the Humboldt current associated with upwelling or downwelling?
    

            upwelling

25. Is the Gulf Stream a broad, shallow, weak current or a narrow, deep, strong current?

            narrow, deep, strong (fast) current

26. What are areas in the ocean where bottom water forms called?

            source area

27. Where are the freshest ocean waters are typically found?        

            near the Equator

28. During El Niño events, are sea surface temperatures abnormally warm or cool off the coast of South America?

            warm

29. In what culture’s literature are the earliest written records of El Niño impacts found?

            Chimu Dynasty in the Moche Valley of Peru

30. Do El Niño events have global effects?

            yes

31. What is the direct conversion of water vapor into ice within a glacier called?

            deposition

32. In western Canada, has the spring melt been occurring earlier or later with each passing year since approximately 1955?
    

            earlier

 

33. Depending on individual eruption characteristics, what effect on net surface cooling or warming can sulfur dioxide and atmospheric aerosols of volcanic origin trigger?

            can trigger both net surface cooling and warming

34. Surprisingly, which region of Africa has experienced permafrost in recent years?

            Mount Kilimanjaro

35. From what locations in the ocean do source areas provide water to the ocean depths?

North Atlantic: near Iceland; South Atlantic: near Antarctica and the area east of the southern tip of South America; North Pacific: Aleutian Islands; South Pacific: near 65° S latitude 

36. What type of currents drive deep ocean currents?
    

            thermohaline currents (circulation)

37. During normal Walker circulation conditions, over what continent is high pressure located?

            South America

38. What is the relationship between pressure gradient force and the Coriolis effect that causes geostrophic flow to occur in the ocean?

PGF (gravity) pushes water outward (downward), while the Coriolis effect (manifested as the Ekman spiral) pushes water inward. As the water circulates clockwise (in the northern hemisphere) along this mound, it reaches an equilibrium between the two forces.

39. A massive conveyor current connects all except which ocean basin?

            Arctic Ocean 

40. What role do dimethyl sulfides play in regulating temperature over the oceans?

Produced by plankton, DMS is transferred to the atmosphere where it oxidizes to form sulfur dioxide and sulfate aerosols. The sulfate aerosols may act as condensation nuclei by encouraging the condensation of water vapor around them, which in turn stimulates the number and thickness of clouds. Increased cloudiness reflects more insolation from the cloud tropics, which may regulate the original cause of higher ocean temperatures – increased energy at the surface.

41. What environmental problem can domestication of grazing animals lead to in semiarid regions?

            desertification

42. The Stommel model indicates that net sinking motions are initiated in the North Atlantic near what country?

            Iceland

43. What is the relationship between accumulation and ablation that determines where the

equilibrium line is within a glacier?

            where the rate of accumulation equals the rate of ablation

44. During El Niño events, into how many branches may the polar front jet stream split?

            2 (north, south)

45. What is a trough?

An elongated area of low atmospheric pressure on a map; an Equatorward dip in airflow

46. What is another name for the Holocene Epoch that has recently been assigned in order to stress the role of humans in shaping the climate?

            Anthropocene Epoch

 

47. What type of phases does the Pacific Decadal Oscillation (a Pacific phenomenon tied to ENSO strength and frequency) involve?

            warm and cold

 

48. What is the boundary between warm surface waters and colder deep waters called?

            thermocline

 

49. What are the surface winds that are equatorward extensions of the subtropical high in the northern hemisphere known as?

            northeast trade winds

 

50. What is a pool of warm water moving eastward while surface waves propagate westward called?

            equatorial Kelvin wave