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  3. While there have been countless attempts at correlating sunspot cycl

While there have been countless attempts at correlating sunspot cycl

游客2024-01-11  42
问题             While there have been countless attempts at correlating sunspot cycles with
       such diverse phenomena as the economy, crop yields, and the weather, there has
       been little evidence to support these correlations. The past few decades have
Line    seen a renewed interest in the sun-climate relationship with a comprehensive
(5)      analysis of many different historical records of solar observation. Late in the
       seventeenth century, a period known as the Maunder Minimum, there were
       virtually no sunspots observed, indicating a "quiet" period in the sun’s activity
       coinciding with the height of a time known as the Little Ice Age, a period of
       lower temperatures in Europe. Once this evidence had been synthesized, it has
(10)     become much clearer that there are indeed robust correlations between the
       Earth’s temperature and sunspots. Perhaps the most important development in
       the solar-climate link came when satellites were developed to measure, in rough
       terms, the Total Solar Irradiance (TSI), a factor shown to be directly related to
       these "activity" cycles. At the maxima of these cycles, there are more sunspots
(15)     (magnetic phenomena that attenuate local irradiance), but new instruments
       show that these dark sunspots are more than compensated for by bright areas on
       the sun called faculae; therefore, the overall irradiance increases in
       correspondence with higher numbers of sunspots.
           Unfortunately, identifying this evident increase in minimum values as a
(20)     trend provokes concern, as there have been only two minima ever measured in
       this way. We must be aware that the warming trend in the surface temperature
       goes far beyond the last two decades, and that an extension of the solar record
       is necessary to assess whether solar activity and irradiance is indeed increasing
       at the minima of the cycles and what the potential effect on the climate may be.
(25)     The solar record has been extended by the use of the historical sunspot records
       already mentioned and correlations have been drawn between solar irradiance
       and the temperature curve since 1610, suggesting a predominant solar influence
       in the pre-industrial period. But since 1860 only half the observed warming
       could be attributable to the irradiance increase, indicating that some other
(30)     influence is becoming more influential in controlling the temperature change:
       most likely industrial carbon-dioxide.
           Recent studies of global warming have necessitated a more comprehensive
       effort to quantify the natural climate variability so that the residual change may
       be attributed to the anthropogenic emissions of greenhouse gases. This attempt
(35)     at quantification of the many different forces effect on the climate has re-
       emphasized the complexity of the climate system and the simultaneous
       interaction of many influences. Solar irradiance may indeed account for some of
       the temperature increases recorded over the last several decades, but as the
       atmospheric CO2 rises, due to the exponential increase in emissions from
(40)     industrial sources, the influence of solar variability on the Earth’s climate will
       most likely decrease, and its relative contribution will be far surpassed by
       "greenhouse" gases. [br] According to the passage, sunspot cycles have which of the following characteristics?
选项 A、During the minima phase of the cycle, there is lower overall irradiance but greater local irradiance, and fewer sunspots.
B、During the minima phase of the cycle, there is greater overall irradiance but lower local irradiance, and fewer sunspots.
C、During the maxima phase of the cycle, there is lower local irradiance but greater overall irradiance, and more sunspots.
D、During the maxima phase of the cycle, there is lower overall irradiance but greater local irradiance, and more sunspots.
E、During the maxima phase of the cycle, there is lower overall irradiance but greater local irradiance, and fewer sunspots.
答案 C
解析
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