The Year Without Summer Read Online Free PDF Page A

year—climatologists
     have determined that 1816 was the second-coldest year in the Northern Hemisphere since
     1400, surpassed only by 1601, following the eruption of Huaynaputina in Peru. Even
     as the aerosol began to settle out of the atmosphere through gravity, it would take
     years for land and ocean temperatures to return to normal. And so 1817 was the fifth
     coldest, 1818 the twenty-second coldest, and 1819 the twenty-ninth coldest year in
     the Northern Hemisphere since 1400.
    In the meantime, the aerosol cloud had produced other noticeable optical phenomena,
     most notably a series of spectacular red, purple, and orange sunsets in London in
     the summer and autumn of 1815. Observers noted repeatedly that “the sky exhibited
     in places a fire,” with “crimson cirri” [high-altitude cirrus clouds, composed of
     fine ice particles] and “much redness in the twilight.” “The evening twilight has
     been generally coloured of late,” wrote one contemporary, “and at times streaked with
     converging shadows, the origin of which could not be traced to clouds intercepting
     the light.” On several particularly unsettled September nights, the storm clouds continued
     to glow various shades of red for half an hour after sunset.
    Sunsets typically appear yellow, orange, or red because atmospheric gases scatter
     blue light more effectively than other colors, skewing the visible-light spectrum
     toward red. The effect is even more pronounced when the sun is low on the horizon,
     since its light must pass through a thicker layer of the atmosphere to reach the ground,
     resulting in less blue and more red light.
    Stratospheric ash, dust, and soot particles from volcanic eruptions—or from pollution
     or fires—enhance this atmospheric scattering effect, leading to brilliant red sunsets.
     After the sun passes below the horizon and light no longer reaches the surface, some
     sunlight still passes through the upper portions of the atmosphere. Aerosol veils
     reflect this sunlight toward Earth, giving the colorful postsunset glows reported
     in London. So exceptional were these sunsets that Londoners commented on them repeatedly
     in letters, journals, and newspaper articles, which suggests that they likely were
     caused by the Tambora aerosol cloud rather than the heavy industrial pollution that
     habitually afflicted the city during that era. In fact, scientists have taken advantage
     of this effect by using the amount of red in contemporary paintings of sunsets to
     estimate the intensity of volcanic eruptions. Several Greek scientists, led by C.
     S. Zerefos, digitally measured the amount of red—relative to other primary colors—in
     more than 550 samples of landscape art by 181 artists from the sixteenth through the
     nineteenth centuries to produce estimates of the amount of volcanic ash in the air
     at various times. Paintings from the years following the Tambora eruption used the
     most red paint; those after Krakatoa came a close second.
    *   *   *
    A MERICANS greeted the year 1816 with confidence and optimism. They had recently concluded two
     and a half years of war with Great Britain, arguably the strongest and certainly the
     wealthiest nation in the world, and the conflict had ended essentially in a draw.
     Admittedly the British had captured and partially burned the nation’s capital, forcing
     President Madison and his wife, Dolley, to flee for their lives, accompanied by several
     wagons full of White House valuables and Cabinet papers stuffed into trunks. But American
     troops led by General Andrew Jackson had ended the fighting on such a positive note
     with their overwhelming victory over a numerically superior force of British regulars
     at New Orleans in January 1815, that many Americans believed they had actually won
     the War of 1812.
    European events since that time offered hope that the United States could look forward
     to a long period of peace, undisturbed by events abroad. On