July 14, 19 10] 



NATURE 



59 



■lesponding with ^° C. 

 i-speclively. The arro\ 



MODELS OF METEOROLOGICAL CONDI- 

 TIONS IN THE FREE AIR. 



THE photographs of which Figs, i and 2 are reproduC' 

 tions are views of two glass models constructed ai 

 the Meteorological Office 

 to represent the tempera- 

 tures and pressures in a 

 block of atmosphere fifteen 

 miles thick over a tri- 

 angular portion of the 

 British Isles on July 27 

 and 29, 1908. 



Records of pressure and 

 temperature were obtained 

 by means of balloons 

 carrying small meteoro- 

 graphs, designed bv Mr. 

 W. H. Dines, F.R.S. 

 Corresponding values of 

 pressure, temperature, and 

 height were computed 

 from the records. 



Balloons were liberated 

 at Ditcham Park, Peters- 

 field ; Pyrton Hill, Oxford- 

 shire ; Glossop, Derby- 

 shire ; Crinan, -'\rgyil- 

 shire ; and Birdhill, Co. 

 Limerick. The courses of 

 the balloons were in some 

 cases traced for part of 

 the way by means of 

 theodolite observations. 



The purpose of the 

 models is to give a repre- 

 sentation of the informa- 

 tion thus obtained, and to 

 exhibit the meteorological 

 variations in three dimen- 

 sions. Each model con- 

 sists of a rectangular base, 

 upon which is drawn an 

 outline map of a portion 

 of the British Isles on the 

 scale of 25 miles to an 

 inch, together with iso- 

 bars and winds for 6 p.m. 

 on one or other of the 

 two days. Upon the base 

 are erected vertical glass 

 plates, secured at the top 

 bv a horizontal plate. In 

 F'ig. I (July 27) the 

 vertical edges of the pris- 

 matic shell thus formed, 

 from left to right, stand 

 over the above-named 

 stations in order, Birdhill 

 being the corner shown at 

 the back. In Fig. 2 

 (July 29) Ditcham is re- 

 presented only by a 

 standard bearing arrows 

 to show wind direction. 

 The recording instrument 

 sent up from that station 

 on that day has not been 

 found. 



Distances measured ver- 

 tically along the glass 

 sides of the models repre- 

 sent heights above sea- 

 level on the scale of 5 

 miles to 4 inches. Tlie 

 vertical scale of the model 

 is therefore twenty times 

 the horizontal scale of th% 

 map. The total height represented is 24 kilometres (15 

 miles). 



The observations from each station are plotted on the 

 edge? of the models. Isotherms (full lines) are drawn on 



NO. 2124, VOL. 84] 



the glass sides for every 5° C, the temperature being ex- 

 pressed in absolute measure. The space between the 

 isotherms of 270° and 275° is filled in to indicate the posi- 

 tion of the freezing point. 



Both models show clearlv the two main divisions of the 



July :?7, 190S. Block seen from the 

 pace between the isotherms o 

 overed. The beaded lines in t 

 1 the standards face the wind i 



n. Isotherms are shown for each 5' 

 d 275" is tilled in ; for other isotherms 

 phere are isobars for 02 megabar and 

 ined by observations with theodolites. 



,-en on July 

 .Absolute from 285° A. to 205° A. The 

 a thickness corresponding with i° C. is 

 o'l megabar respectively. The arrows ( 



Isotherms are shown for each 5 

 of 270° and 273° is filled in ; for other isotherms 

 overed. The beaded lines in the stratosphere are isobars for o;2 megabar and 

 1 the standards face the wind as determined by observations with theodolites. 



atmosphere, viz. : — (i) " troposphere," or lower portion, in 

 which temperature diminishes with height at a nearly 

 uniform rate and the isothermal surfaces are approxi- 

 mately horizontal, and (2) "isothermal region," or 



