METEOROLOGY, 



489 



Observations were made between 1882 and 

 1886, by Mr. W. Marriott at the church-tower 

 of Boston, England, of temperatures at 4 feet, 

 170 feet, and 260 feet above the ground. The 

 results showed that the mean maximum tem- 

 perature at 4 feet exceeds that at 170 feet in 

 every month of the year, the difference in the 

 summer months amounting to 3 ; while the 

 mean minimum temperature at 4 feet differs but 

 little from that at 170 feet, the tendency, how- 

 ever, being for the former to be slightly higher 

 in the winter and lower in the summer than 

 the latter. As indicated by the readings of the 

 electrical thermometer which was depended 

 upon for the observations at the third height, 

 the temperature at 4 feet during the day hours 

 was considerably higher than at 260 feet. 



Comparative observations of the ranges of 

 temperature are made under the direction of 

 the New England Meteorological Society at 

 high and low level stations in the White mount- 

 ain region. The results of those made in June 

 go to show that while the nocturnal mimima in 

 the deep valleys are, during the occurrence of 

 high pressure, almost as low as on Mount 

 "Washington, the diurnal maxima are much 

 higher at the lower than at the summit sta- 

 tions, and indeed are, on clear, sunny days, al- 

 most as high in the White mountain valleys as 

 anywhere in New England. 



In his discussion of the relative capacity of 

 the solid crust of the earth and of the waters 

 to propagate heat, M. Woeikof concludes that 

 a considerable part of the heat of the globe is 

 lost in space by the radiation in the higher 

 latitudes from the surface of the ocean. The 

 loss is manifested by the accumulation of ex- 

 tensive masses of cold water at the bottom of 

 the ocean. Between 20 of north and 20 

 south latitude, the deep-sea temperature is re- 

 duced to 4 C. principally by the influence of 

 under-currents moving slowly from the Ant- 

 arctic Ocean toward the equator. As the 

 superficial temperature of the ocean is but 

 little changed by this, so the accumulation of 

 cold water in the bottom has but little influ- 

 ence; yet the greatest loss which the earth 

 suffers appears to proceed from the radiation 

 from the seas, particularly from the polar seas. 



The examination of the isothermal charts 

 for February and August has led Zrummel to 

 the conclusion that two thirds of the surface 

 of the ocean is constantly at a temperature of 

 more than 24 0., and more than half of it 

 above 20. The waters of the northern hem- 

 isphere appear to be decidedly warmer than 

 those of the southern hemisphere. 



Clouds. The phenomenon of iridescence in 

 clouds is presented when in light cirro-cumu- 

 lus cloud the borders of the clouds and their 

 lighter portions are suffused with soft shades 

 of color like those of mother-of-pearl. Usually 

 the colors are distributed in irregular patches, 

 just as in mother-of-pearl; but occasionally 

 they form round the denser patches of cloud a 

 regular colored fringe, in which the several 



tints are arranged in stripes following the 

 sinuosities of the outline of the cloud. Seek- 

 ing for an explanation of the phenomenon, G. 

 Johnstone Stoney shows that on account of 

 the low temperature at the elevation in the at- 

 mosphere at which these clouds are formed, 

 water can not exist in the liquid state, but the 

 vapor from which the clouds are condensed 

 passes at once to the solid form of tiny crys- 

 tals of ice. If the vapor has been evenly dis- 

 tributed, and the precipitation has taken place 

 slowly, the crystals in any one neighborhood 

 will be of nearly the same form and size, and 

 from one neighborhood to another they will 

 differ chiefly in number and magnitude. This 

 will give rise to a patched appearance of the 

 clouds. When the conditions prevailing in 

 any one neighborhood of the sky are such as 

 to produce lamellar crystals of nearly the same 

 thickness, these tabular plates will be subsid- 

 ing through the atmosphere. Although their 

 descent is very slow, the resistance of the air 

 will act upon them, in consequence of their 

 minute size, as it does upon a falling feather, 

 and will cause them, if disturbed, to oscillate 

 before they settle into a horizontal position. 

 If the crystals are plates with parallel faces, 

 since they are also transparent, a part only of 

 the sun's ray that reaches the front face will 

 be reflected from it; the rest will enter the 

 crystal, and, falling on the parallel surface be- 

 hind, a portion will be there reflected, and, 

 passing out through the front face, will also 

 reach the eye of the observer. These two 

 portions of the ray that reflected from the 

 front face and that reflected from the back 

 are precisely in the condition in which they 

 can interfere with one another, so as to pro- 

 duce the splendid colors with which we are 

 familiar in soap-bubbles. The phase of the 

 phenomenon in which the colors form definite 

 fringes around the borders of the cloudlets is 

 accounted for by observing that so long as the 

 cloud is in the process of growth the crystals 

 will keep augmenting. In this case, the patch 

 of cloud may consist of crystals which are 

 largest in its central part, and gradually smaller 

 as their situation approaches the outside ; and 

 we have the conditions which will produce one 

 color around the margin of the cloud, and other 

 tints farther in. 



In a discussion on the nomenclature of clouds, 

 Prof. Koppen intimates the question whether 

 the same cloud seen from different sides should 

 receive different names, or whether the classi- 

 fication should refer generally to the proper- 

 ties observed in a particular cloud, especially 

 as regards its density and dimensions. The 

 apparent form, which is important in Poey's 

 classification, is shown to lead sometimes to 

 erroneous conclusions. In a report of a con- 

 ference between the Hon. R. Abercromby and 

 Mr. Hildebrandsson at Upsala, which is em- 

 bodied in the paper, it is pointed out that tho 

 study of the forms of clouds may be under- 

 taken with different objects in view. If the 



