The Philosophy of the Weather Part 14

The investigations of Lieutenant Maury show, that when the Gulf Stream turns to the eastward, crossing the lines of declination at right angles, as the counter-trades also seem to do in the same lat.i.tude, it is _carried up, in summer, several degrees to the north_, and descends again in winter--thus demonstrating its connection with the shifting magnetic machinery which controls alike the ocean, the atmosphere, and the temperature of the earth.[7]

There are other irregularities which deserve to be noticed, in this connection, although the a.n.a.logical evidence they afford is far from being decisive.

I have already said that it was within my own observation, that alternating lines of heat and cold, as well as rain and drought, existed frequently, without regard to lat.i.tude, following, to some extent, the course of the counter-trade. Such lines have been observed by others.

Thus, Mr. Espy, after describing a snow-storm, which was followed by a very cold N. W. wind, of several days' continuance, says:

"This cold air covered the whole country, from Michigan to the eastern coast of the United States, till the beginning of the great storm of the 26th January; and, what is worthy of particular notice is, that _the temperature began to increase first in the north and north-west_. On the morning of the 25th, in the north-western parts of Pennsylvania, and northern parts of New York, the _thermometer_ had already _risen in some places 30_, and, in others, _above 40_.

While in the S. E. corner of Pennsylvania, and in the S. E. corner of New York it had not _begun to rise_. The _wind_ also began to change from the _north-west_ to _south_ and _south-east_, _first_ in the north-west parts of Pennsylvania and New York, some time before it commenced in the south-east of those States; and, during the whole of the 25th, the thermometer, in the north of New York, continued to rise, though the wind was blowing from the southward, where the thermometer was many degrees lower."

Thus, too, Mr. Redfield (American Journal of Science, November, 1846, p.

329):

"On the contrary, in times of the greatest depression of the thermometer, in numerous instances, the cold period has been found to have first taken effect in, or near, the tropical lat.i.tudes, and the Gulf of Mexico, and has thence been propagated toward the eastern portions of the United States, in a manner corresponding to the observed progression of storms."

This was because the cold N. W. wind which _followed_ storms began to follow them as the storms curved and pa.s.sed to the N. E.

They occur in Europe also. Says Kamtz:

"Such contrasts are not uncommon in Europe, and, in this respect, the Alps form a remarkable limit; for they separate the climates of the north of Europe from the Mediterranean climates, where the distribution of rain is not the same as in the center of Europe.

Hence the differences between the climates of the north and south of France. _If the winter is mild in the north_, the newspapers are filled with the lamentations of the _Italians_ and _Provencals_ at the _severity of the cold_."

These facts seem to indicate a primary action in the counter-trade.

Probably in connection with one cla.s.s of storms they do, and with another do not. I shall endeavor to show the distinction when I come to the cla.s.sification of storms.

The difference of seasons in this country, and over the entire northern hemisphere, is often very great. In a remarkable work of a remarkable man--"A Brief History of Epidemic and Pestilential Diseases," by Noah Webster, published in 1799, 2 vols.--a history of the weather for about two centuries--1600 to 1799 inclusive, is given generally, and then in a tabular form. Those who think that every considerable extreme which occurs exceeds any thing before known, will do well to consult that work.

Droughts are described, where "there was not a drop of rain for three or four months, and cattle were fed upon the leaves of the trees." Winters, so intensely cold that the thermometer fell to 20 below zero, at Brandywine; or so mild that there was little frost, and people upon Connecticut River plowed their fields, and the _peach trees blossomed in Pennsylvania in February_. These extremes generally existed in Europe and America at the same time, but occasionally they were opposite and alternate. Says Mr. Webster, in summing up the facts (vol. ii. p. 12): "It is to be observed that in some cases a severe winter extends to both hemispheres, sometimes to one only, and in a few cases to a part of a hemisphere only. Thus in 1607-8, 1683-4, 1762-3, 1766-7, 1779-80, 1783-4, the severity extended to both hemispheres. In 1640-41, 1739-40, and in other instances, the severe winter in Europe preceded, by one year, a similar winter in America. In a few instances, severe frost takes place in one hemisphere during a series of mild winters in the others; but this is less common. In general, the severity happens in both hemispheres at once, or in two winters, in immediate succession; and, as far as this evidence has yet appeared, this severity is closely attendant on volcanic discharges, with very few exceptions."

It will be seen that Dr. Webster (LL.D. and not M.D., and therefore the remarkable character of the work) attributes great influence to earthquakes and volcanic action. Probably he is correct in this. The present active volcanic action of the western hemisphere is nearly all within the trade-wind region, from Mexico to Peru inclusive. The West India islands are of volcanic origin, and the influence of volcanic action is not confined to a concussion of the earth, or the eruption of mud and lava. Its connection with magnetic action, and disturbance, is unquestionable. But whether they operate to increase or diminish the trades, and the extent to which they induce violent electric action and storms within and without the tropics, is a question which further observation must determine. The ripples of the ocean, compared by Lieutenant Banvard to that of a "boiling cauldron, or such as is formed by water being forced from under the gate of a mill-pond," are met with in the vicinity of volcanic islands, where hurricanes and water-spouts originate, and have been observed to precede storms, and be connected with a falling barometer. But whether they are volcanic or magneto-electric, it is difficult to determine. Dr. Webster remarks, as the result of observation, during the 17th century, that earthquakes had a N. W. and S.

E. progression in the United States, and especially in New England. In a recent article, Professor Dana has examined, with great ability, the general and remarkable trending of coast lines, groups of islands, and ranges of mountains, from N. E. to S. W. and from N. W. to S. E. (American Journal of Science, May, 1847.)

The line of magnetic intensity, which connects our magnetic pole with its opposite, is now upon this continent nearly a N. W. and S. E. line, and the pole is fast traveling to the west. It may, and probably will yet, be established, that there is an intimate connection between the cause of volcanic action within the earth, to which the upheaval of the N. W. and S. E., and N. E. and S. W. ranges were due, and of magnetic action without, and between both, and the cause of _the S. E. extension_ of our summer storms and belts of showers and barometric _waves_, and the _peculiar N. W. wind_. Our limits do not permit us to pursue the subject.

Much influence upon the weather has been attributed to the spots upon the sun. These spots are supposed to be breaks or openings in the luminous atmosphere or photosphere of the sun, through which its dark nucleus body is seen. Counselor Schwabe, of Dessau, has made them his study since 1826, and has arrived at some singular results. They seem to be numerous--in groups--and to appear periodically with minima and maxima of ten years.

As the result of his observations, from 1826 to 1850, he gives us the following table and remarks:

+-----------------------------------------------+ Year. Groups. Days showing Days of no spots. Observation. ------- --------- -------------- -------------- 1826 118 22 277 1827 161 2 273 1828 225 0 282 1829 199 0 244 1830 190 1 217 1831 149 3 239 1832 84 49 270 1833 33 139 267 1834 51 120 273 1835 173 18 244 1836 272 0 200 1837 333 0 168 1838 282 0 202 1839 162 0 205 1840 152 3 263 1841 102 15 283 1842 68 64 307 1843 34 149 312 1844 52 111 321 1845 114 29 332 1846 157 1 314 1847 257 0 276 1848 330 0 278 1849 238 0 285 1850 186 2 308 +-----------------------------------------------+

"I observed large spots, visible to the naked eye, in almost all the years not characterized by the minimum; the largest appeared in 1828, 1829, 1831, 1836, 1837, 1838, 1839, 1847, 1848. I regard all spots, whose diameter exceeds 50", as large, and it is only when of such a size that they begin to be visible to even the keenest unaided sight.

"The spots are, undoubtedly, closely connected with the formation of faculae, for I have often observed faculae, or narben, formed at the same points from whence the spots had disappeared, while new solar spots were also developed within the faculae. Every spot is surrounded by a more or less bright, luminous cloud. I do not think that the spots exert any influence on the annual temperature. I register the height of the barometer and thermometer three times in the course of each day, but the annual mean numbers deduced from their observations have not hitherto indicated any appreciable connection between the temperature and the number of the spots. Nor, indeed, would any importance be due to the apparent indication of such a connection in individual cases, unless the results were found to correspond with others derived from many different parts of the earth. If the solar spots exert any slight influence on our atmosphere, my tables would, perhaps, rather tend to show that the years which exhibit _a larger number of spots_ had a _smaller number of fine days_ than those exhibiting few spots."

These observations _seem_ to show that the spots exert no influence upon the weather, and to be satisfactory. But, perhaps, they are not entirely so. No effect would, of course, be expected from day to day, and perhaps the annual mean may not be seriously disturbed, and yet the spots may seriously affect the seasons. Popular tradition has fixed upon certain periods, of 10, 20, and 40 years, for the return of winters of unusual severity; and the tables of Mr. Webster, and other facts, show that it is not wholly without foundation. If we, and those we have cited, are not mistaken in most of the views expressed, the natural effect of a partial interception or failure of the sun's rays, by or from the existence of the spots, would be to decrease the exciting power of the solar rays upon terrestrial magnetism, and, as a consequence, the volume of the trades and their amount of moisture. This would increase the _mean_ heat of the summer in the temperate zone--for the _less_ the volume of trade, the less precipitation and variable wind, and succeeding polar waves of cooler air, and the greater mean heat. On the other hand, the same cause, and the feebler heating power of the sun's rays, would make the winters more severe, both from an absence of a portion of heat, derived directly from the sun's rays, and a less mitigating influence, from the action of the trade, by reason of its decreased volume. So, too, the absence of spots, and a more powerful influence from the solar rays, may gradually carry the machinery further north in summer, and further south in winter, and thus make the _seasons extreme_ without seriously disturbing the mean of the year. And both these may occur in a more marked degree over our intense magnetic area than in Europe. I am satisfied that they do so occur. That the partial failure of the sun's rays limits the transit of the machinery, and the volume of the trades during the latter half of the decade, and extends the transit and increases the volume during the first half, producing an occasional severe summer drought and severe winter, in the warmest portion of the decade. And that the variations correspond with the difference in the character and number of the spots in different decades, and hence the longer and shorter periods.

Turning to the tables of Dr. Webster, we find that a general tendency to extreme seasons does seem to exist from the 6th to the 10th year of every decade, and especially of every alternate decade. The periods of 1707-8, 1728, 1737 and 1739, 1749-50, 1758-9, 1779-80, 1798-9, are those in which the tendency was seen most decided. These tables are very general. The thermometer was not perfected till about 1700, and did not get into general use before 1750. There were very few meteorological registers kept, or accessible to Dr. Webster. Hence he was obliged to resort to such other sources of information as were open to him, and such statements as he found are not always entirely reliable. The oldest inhabitant is apt to express himself very strongly respecting present extremes, and fail somewhat in his recollection of those which have past. Still his tables afford general and obvious evidence of the regularity of those periodic conditions.

+---------------------------------------------------------+ A. D. Summer. Winter. ----- ------------------------- ------------------------- 1701 hot and dry .... 1702 hot and dry .... 1703 .... .... 1704 dry Europe .... 1705 .... .... 1706 hot, dry Europe .... 1707 very hot .... 1708 .... very severe 1709 .... .... 1710 .... .... 1711 .... cold Europe 1712 wet England .... 1713 wet England mild 1714 dry and hot .... 1715 dry .... 1716 very dry severe 1717 .... severe 1718 hot and wet .... 1719 .... cold America 1720 dry Europe .... 1721 .... .... 1722 cold, wet .... 1723 .... cold 1724 wet England .... 1725 wet England .... 1726 .... .... 1727 dry, hot Amer. .... 1728 hot Amer. severe Europe 1729 .... .... 1730 .... very cold Eng. 1731 .... .... 1732 .... severe Amer. 1733 dry Eng. .... 1734 .... .... 1735 wet .... 1736 wet .... 1737 .... very severe Am. 1738 .... .... 1739 wet England very severe Eng. 1740 .... very severe Am. 1741 .... .... 1742 .... severe Syria 1743 hot .... 1744 .... .... 1745 .... .... 1746 .... .... 1747 hot and dry severe 1748 dry .... 1749 very dry .... 1750 very hot very severe 1751 wet England severe Amer. 1752 very hot Amer. .... 1753 .... severe 1754 .... mild Amer. 1755 .... severe Europe 1756 .... severe Syria 1757 .... .... 1758 hot .... 1759 .... severe 1760 .... .... 1761 very dry Amer. .... 1762 very dry Amer. severe 1763 .... .... 1764 hot Europe .... 1765 hot Europe severe Europe 1766 hot and dry Eur. very severe 1767 .... cold 1768 hot .... 1769 hot .... 1770 wet England .... 1771 wet Am. & Eng. cold Europe 1772 hot America Am., great snow 1773 .... .... 1774 .... severe Europe 1775 .... .... 1776 hot severe Europe 1777 .... .... 1778 hot mild 1779 hot Eng. very severe 1780 .... .... 1781 .... .... 1782 dry Amer. .... 1783 hot very severe 1784 hot .... 1785 dry Europe cold 1786 cool cold 1787 cool .... 1788 rainy Amer. cold 1789 cool spring, hot summer severe Eur., mild Amer. 1790 .... .... 1791 very hot Am. cold 1792 .... .... 1793 hot, dry Am. mild Amer. 1794 .... severe Europe 1795 Amer., hot, rainy .... 1796 Autumn very Dry Am. cold Amer. 1797 cool Am. severe Amer. 1798 very hot } { long & severe 1799 very dry Am. } { Amer. & Eur. +---------------------------------------------------------+

Still more definite evidence is found in the meteorological tables of Dr.

Holyoke and Dr. Hildreth, and an account, by Dr. Hildreth, of the seasons when the Ohio River was closed or obstructed by ice, found in Silliman's Journal, new series, vol. xiii. p. 238.

Thus, we have, from the tables of Dr. Holyoke, the following annual means, from 1786 to 1825, inclusive. I have arranged them in periods of five years. It will be seen that there are three peculiarities observable.

First, a marked difference between the first and second periods of the decade, corresponding, generally, with the presence or absence of the spots. Second, a difference in the mean of the decades which may well be supposed to correspond with the difference in the number or size of the spots since a like difference is observable in number and size, and the time when they reached their maxima and minima, in the table of Schwabe.

And, third, there are occasional single cold years during the warm period, and these correspond with what the tables of Dr. Webster show for both the sixteenth and seventeenth centuries. In relation to this, it should be remembered that volcanic action is a frequent and powerful disturber of the regular action of terrestrial magnetism, and that the extremes, for that reason, are frequently meridional or local and alternating; and to that cause very great extremes, and marked exceptions, may be due, notwithstanding the spots upon the sun may exert an influence in producing hot summers and cold winters toward the close of each decade. Thus, to select an instance to ill.u.s.trate this and explain an anomaly: The coldest season during the whole period, embraced in the following tables, is that of 1812. This occurs during the decrease of spots, and the warm half of the decade. Turning to the table of volcanic action, and of earthquakes, found in the Report of the British a.s.sociation for 1854, we find that year was remarkable for earthquakes in the United States and South America. In December, 1811, earthquakes commenced in the valley of the Mississippi, Ohio, and Arkansas, felt also at places in Tennessee, Kentucky, Missouri, Indiana, Virginia, North and South Carolina, Georgia, and Florida, though not so severely east of the Alleghanies, _which continued until 1813_.

About the same time they commenced in Caraccas, and, in March, 1812, became severe over the greater portion of the northern section of South America, and in the Atlantic. No such general and continued succession of earthquakes occurred during the other periods embraced in the tables, and the mean of the following five years was very low, embracing the memorable cold summer of 1816.

+---------------------------------------------------------------+ Cold Period. Warm Period. Cold Period. Warm Period. --------------- --------------- --------------- --------------- 1786 48.53 1791 48.963 1796 48.678 1801 50.432 1787 47.88 1792 48.44 1797 48.135 1802 50.794 1788 47.676 1793 50.96 1798 49.471 1803 50.24 1789 47.68 1794 50.768 1799 48.291 1804 48.328 1790 46.53 1795 50.173 1800 49.989 1805 50.792 --------------- --------------- --------------- --------------- Mean of period 47.659 Mean 49.901 Mean 48.910 Mean 50.117 --------------- --------------- --------------- --------------- --------------- --------------- --------------- --------------- 1806 47.982 1811 50.76 1816 47.113 1821 48.15 1807 48.132 1812 45.28 1817 46.277 1822 49.81 1808 49.485 1813 47.702 1818 48.009 1823 47.58 1809 47.92 1814 48.279 1819 50.75 1824 49.25 1810 49.001 1815 47.607 1820 48.70 1825 50.99 --------------- --------------- --------------- --------------- Mean 48.505 Mean 47.925 Mean 48.169 Mean 49.15 +---------------------------------------------------------------+

The tables of Dr. Hildreth, from 1826 to 1854, inclusive, furnish, generally, evidence of a like character. There are, however, an anomaly or two which will be observed. From 1826 to 1830, the mean is high during the period when spots were at a maximum. But that maximum embraced a much less number of spots than the two succeeding ones. A contrast appears in the tables of Dr. Hildreth, during the early period, for Dr. Holyoke's register, for 1827, puts it _below the mean_, but Dr. Hildreth's one of the _highest of the half century_. In 1835 commenced a period when the spots were much more numerous, and from 1835 to 1838, inclusive, the seasons were correspondingly below the mean. From that period to 1844 a gradual and slightly irregular rise took place, excepting the year 1843, when another cold year intervened. The table of earthquakes, published by the British a.s.sociation, closes with 1842, and I have not access to any others. The occurrence of such cold years, in the warm period, at intervals during the two centuries previous, and in 1812, and onward, and evidently owing to increased volcanic action beneath the western portion of the northern hemisphere, justifies the belief that the low temperature of 1843 was owing to the same cause. The following are the means from the tables of Dr. Hildreth:

+----------------------------------------------------------------+ 1826 54.00 1831 50.87 1836 50.03 1841 52.18 1846 53.64 1827 54.92 1832 52.42 1837 51.57 1842 52.83 1847 52.00 1828 55.22 1833 54.56 1838 50.62 1843 50.77 1848 52.50 1829 52.38 1834 52.40 1839 52.54 1844 53.25 1849 52.09 1830 54.93 1835 50.65 1840 52.35 1845 52.73 1850 51.48 ------------ ------------ ------------ ------------ ------------ Mean 54.29 Mean 52.18 Mean 51.52 Mean 52.35 Mean 52.32 +----------------------------------------------------------------+

The observations of Dr. Holyoke were made at Salem, Ma.s.sachusetts; those of Dr. Hildreth at Marietta, Ohio.

The following, in relation to the freezing of the Ohio River, is evidence of a different kind, but shows the same general correspondence, and particularly _the mildness of the winters when there were few spots_, and their severity from 1836 to 1838, inclusive, when the spots were most numerous:

1829.--River open all winter--some floating ice.

1830.--River closed 27th January.

1831.--Floating ice--closed 23d January--opened 20th February.

1832.--Closed in December, which was a very cold month--opened January 8, and remained open all winter.

1833.--Open all winter.

1834.--Open all winter.

1835.--Closed January 6--opened the last of the month--cold.

1836.--Closed 28th January--opened 25th February.

1837.--Closed from 8th December to 8th February. Cold year.

1838.--Closed from 13th January to 13th March. Cold year.

1839.--Closed from 6th December to 13th January.

1840.--Closed 29th December--opened 15th January.

1841.--Closed 3d January--opened 8th do.

1842.--Open all winter.

1843.--Closed 28th November--opened 5th December--open all the rest of the winter.

1844.--Open all winter.

1845.--Open all winter.

1846.--Closed 5th December--opened again a few days--closed again on the 26th. It is not stated how long it remained closed.

1847.--Open all winter.

1848.--Much floating ice, but not closed--heavy rains and floods.

1849.--Floating ice in January, but not closed.

1850.--Floating ice, but not closed.

1851.--Open all winter--a little ice.

(December in the above table, means December previous).

This is more reliable as to the winter season than the tables of annual means--although the evidence they afford, making due allowance for the exceptions, is very striking.

I shall return to this part of the subject again.

But there is other evidence of the influence of these spots. Their connection with the irregular magnetic disturbance of the earth has been distinctly traced. Colonel Sabine, President of the British a.s.sociation, in his opening address, September, 1852, after reviewing the recent discoveries in magnetism, says:--