118 



THE GENESEE FARMER. 



May 



illcteorologtcal Observations, $Zt. 



METEOROLOGY— CLIMATOLOGY. 



BY L. WETHERELL. 



Some account of the variations of temperature upon the sur- 

 face of the earth, icith a statement of some of the causes 

 that produce them. 



That department of meteorology denominated 

 climatology, is of great interest to man in every re- 

 lation of his earthly existence. But none feels a 

 more direct interest in this subject than he whose la- 

 bors are nothing worth unless aided by the seasona- 

 ble distribution of light, heat and moisture. 



The sun is the source of both light and heat, with- 

 out whose rays vegetable and animal life would soon 

 cease from this planet. It is a well known fact that 

 these are not equally distributed over the surface of 

 the earth. This is owing to the following causes, 

 viz: the annual motion of the earth round the sun, 

 the diurnal rotation upon its own axis, the inclination 

 of its poles ; also, the effect of geographical posi- 

 tion, configuration and altitude. In consequence of 

 the earth's annual motion the position of the sun in 

 the heavens apparently changes. The path of the 

 sun thus described is called the elliptic; intersecting 

 the celestial equator at an angle of 23° 28', on the 

 21st of March and September of every year. On 

 each of these days, at noon, the sun's rays fall per- 

 pendicularly upon the earth's surface at every place 

 upon the terrestrial equator, and falling very obliquely 

 at the poles. 



Two imaginary circles are drawn parallel to the 

 equator, each 23^ 28' from it ; the one north is called 

 the Tropic of Cancer, and the one south Ike Tropic 

 of Capricorn. Over that part of the earth's surface 

 embraced between the tropics the heat is distributed 

 with something like equality ; that is to say, unless 

 varied by altitude. 



Geographers have divided the earth into five zones 

 or belts — the first, or torrid zone, is 3,243 miles 

 in breadth, containing 77,700,000 square miles ; 

 second, the two temperate, each about 2,970 miles in 

 breadth, each containing 50,000,000 square miles ; 

 and, third, the two frigid, each 1,663 miles wide, em- 

 bracing each 8,000,000 square miles. Instead of this 

 division the ancients used the word climate to signify 

 that obliquity of the sphere with respect to the hori- 

 zon from which results the inequality of day and 

 night. The day and night are of equal length on 

 the equator — soon varying as the poles are approach- 

 ed either north or south. 



The follow ing table, copied from " Muller's Meteo- 

 rology," will give a very good view of this use of the 

 word climate ; also showing the length of the day in 

 different latitudes : — 



Polar elevation. Length of tlio longest day. 



I) 12 hours. 



li!*leg. '14 min 13 " 



30 " 18 " - 14 " 



4!t '• 22 " - lo' " 



o".{ " 22 " - 20 " 



<;<; " :j-j •' 24 " 



7:i " 39 " - 3 months. 



90 " 6 



Some of the ancients, instead of nine divisions, 

 m: de twenty-lour between the equator and the polar 

 circles, and six between the polar circles and the 

 poles — the former called half-hour climates: because, 

 from one to the other the length of the day is in- 

 creased half an hour; the latter called month cli- 



mates, because between any two of the lines, as the 

 pole is approached, there is a difference of a month 

 in time. 



The annual mean temperature of a belt 1,390 miles 

 wide, embracing 10° each side of the equator, and on 

 a level with the sea-coast, is said to be about 82° — 

 varying, however, whether an eastern or western 

 coast, always higher on the western. The sun be- 

 ing twice vertical in the year to every place lying in 

 the hot zone, every place situated within this belt has 

 two summers and two winters every twelvemonth. 

 The difference of temperature is so trifling as scarce- 

 ly to attract attention. At Cumana, in South Ameri- 

 ca, situated at 10° north lat.tude, the mean tempera- 

 ture of the winter is 80£° ; and that of the three hot- 

 ter months is only 83£°. The mean temperature of 

 Havana, on the island of Cuba, situated 23° n. lat., 

 is 78° ; that of Madras, in lat. 13°, is 81° ; that of 

 Manilla, the principal of the Philippine islands, in 

 latitude 15°, is the same as Havana. The tempera- 

 ture here is remarkable for its equaminity. 



The annual mean temperature of Massowa (Abys- 

 sinia, 15J° s. lat.) 87-6° ; of Mexico, (19J n. lat.) 

 62° ; of Lisbon, (38J° n. l.)61.4° ; of Madrid, (40* 

 n. 1.) 57-4° : Baltimore, (39° n. 1.) 53 ° : of Paris, 

 (49° n. l.)5l.3° ; London, (51 i° n. 1.) 50.9° ; 

 Vienna, (48 n. 1.) 50.1 ° ; of Geneva, (46° n. 1.) 

 49.3 ° ; of Berlin, Edinburgh, Hamburgh, and 

 Tubingen, ^the first 52J ° , the second 53£ ° , and the 

 third 56 ° , and the fourth, 48 J n. 1.) each 47.6 ° ; of 

 Rochester, (43° n. 1.) about 48° : of Petersburg!!, 

 (60 © n. 1.) 38.2 ° ; of North Cape, (71 ° n. 1.) 32.1°: 

 and of Melville Island, (75° n. 1.) 1.75 below zero. 

 The mean temperature of the winter of the last place 

 mentioned, is 28.2 below zero ; of the spring 3.1 be- 

 low ; of the summer 37.1 above: and the autumn 

 0.4 below zero ; the coldest month, February, 35.8 

 below zero. 



As will be well recollected by those who read the 

 article on the "Distribution of Plants," in the last 

 number of the Farmer, it is found to be much colder 

 on the eastern coast of either continent than on the 

 western ; that is when the annual temperature of 

 places on the eastern coast of America is compared 

 with those of the western coast of Europe, a remark- 

 able difference is seen. Nain, on the coast of La- 

 brador, 57 ° n. lat., has an average temperature of 

 26.5 ° ; Christiana, in Norway, 60 ° n. lat., average 

 temperature 42.7 ° . 



The average temperature of Quebec is 42 ° , while 

 that of Amsterdam, 5£ ° further north, has an aver- 

 age temperature of 52 ° . Halifax lies in the same 

 latitude with Bordeaux, New York with Naples. The 

 average temperature of Halifax is 13° lower than 

 Bordeaux; and that of New York 7° lower than 

 Naples. As the equator is approached these differ- 

 ences gradually diminish, as seen by comparing St. 

 Augustine and Cairo: each, situated 30° n. lat.. has 

 almost the same degree of temperature. 



New Archangel, on the west coast of America, has 

 nearly the same lat. as Nain on the opposite coast : 

 yet its average temperature is 19 dog. above that of 

 Nain. Pekin is further south than Naples; yet the 

 former being situated on the eastern coast of Asia, has 

 an average temperature of 9 deg. lower than that of 

 the latter. In the northeast of Ireland, lat. 55 ° , the 

 average temperature of the winter is about 8 deg. 

 above freezing point : here the myrtle thrives as well 

 as in Portugal. On the coast of Devonshire the 



