Essay 13NEW
Since the 1850s researchers have tried to show that variations in seasonal weather are connected in some ways with sunspots, the outward sign of an increase in the Sun's activity. However, sciences lacked evidence supporting such a link until the mid-1980s,when van Loon and Labitzke compiled statistical evidence suggesting that a link exists and that it involves winds in the upper atmosphere above the equator which reverse their direction, from east to west or west to east, every twelve to fifteen months. This phenomenon is called the quasi-biennial oscillation(QBO),and although meteorologists have known about the QBO since the 1950s,until the 1980s no one recognized a subtle but statistically significant link between the QBO and certain pattern of weather. When the west to east direction of winds in the upper atmosphere coincides with periods of high solar activity that occur approximately every eleven years, winters in the eastern and central United States are very cold.
On this basis, some meteorologists predicted that the winter of 1988-1989 in the United States
would be severe. However, the winter was a mild one overall, and the meteorologists' attempt to make the connection between the Sun and weather on the Earth appeared unsuccessful, until Barston and Liverzey proposed a hypothesis explaining why the prediction had failed. They argued that the prediction had not taken into account another important element in the climate: the more or less regular pattern of fluctuations in the temperature of the surface waters of the tropical Pacific Ocean.
Barston and Livezey noted that when the water temperature is abnormally high-the phenomenon called EL Nino—the changces of cold winter weather over North America
increase. The opposite situation, when surface temperatures are well below normal—La Nina—is far less common.In fact, until late 1988 no one had seen the combination of La Nina, westerly winds in the upper atmosphere, and high solar activity. Thus, according to Barston and Livezey,La Nina cancelled out the effect of the other two climatic factors and caused the mild winter of 1988-1989.Although this hypothesis is plausible, much research remains to be done before meteorologists can establish and explain the effects of increased solar activity on seasonal weather changes.
Q39. The author of the passage would most likely agree with which of the following statements about the link between increased solar activity and certain seasonal weather changes on the Earth?
A. Because the evidence supporting such a link is questionable, future research in this particular area does not looking promising.
B. Because it is unlikely that such a link can be definitely established, scientists should concentrate their efforts on investigating the role La Nina and other climatic factors play in influencing global weather patterns.
C. Although some circumstantial evidence suggests that such a link exists, it is unlikely that future research will be able to confirm the existence of this link.
D. There is evidence supporting the existence of such a link, but without further scientific investigation that evidence cannot be considered proof that such a link exists.
E.Since the evidence clearly supports the existence of such a link, further research should focus on determining the implications of this link for the accurate prediction of changes in global weather patterns.
Q40.The passage provides information to support which of the following statement about La Nina?
A. Its occurrences is more likely to coincide with the periods of high solar activity rather than low solar activity.
B. It is more likely to occur when the winds in the upper atmosphere above the equator are blowing from the west rather than from the east.
C. It occurs more frequently than do shifts in the winds in the upper atmosphere above the equator.
D. It occurs less frequently than does increased solar activity.
E. It occurs less frequently than does EL Nino.
Q41.Which of the following most accurately describes the organization of the passage?
A. A hypothesis is presented, a theory is constructed on the basis of the hypothesis, and then further research to expand the scope of the theory is proposed.
B. A hypothesis is presented, an example that contradicts it is described, and then a hypothesis accounting for the apparent contradiction is proposed.
C.Two opposing hypotheses are stated, and evidence confirming one of the hypotheses is considered.
D. A phenomenon is described, a prediction about that phenomenon is made, and evidence confirming the accuracy of the prediction is presented.
E. A prediction about a phenomenon is detailed and evaluated, and evidence demonstrating the inaccuracy of the prediction is presented.
Q42.The passageprovides information to support which of the following statements about the occurrence of very cold winters in the earstern and central United States
?
A. Such winter are most likely to occur if the winds in the winds in the upper atmosphere over the equator blow from the east rather than from the west.
B.Such winters are most likely to occur if increased activity of the Sun coincides with the appearance of La Nina.
C.Such winters are less likely to occur if increased activity of the Sun coincides with the appearance of El Nino.
D. Such winters are less likely to occure if there is an increase in the number of sunspots on the surface of the Sun.
E. Such winters are less likely to occur if there is a drop in the temperature of the surface waters of the tropical Pacific Ocean.
