STORM-TRACK MAP OF THE NORTH ATLANTIC 



The lightly shaded area shows the region of most frequent depressions; the darker areas are favourite points upon which 

 the storms converge, and whence they disperse; while the barbed lines show the general routes they take. 

 B, The British Isles; F, France; S, Spain; G, Greenland; C, Canada; N.A., N. America. 



THE RAPID VARIABILITY OF TEMPERATURE 



Upper line, the "dry "'bulb; lower line, the "wet" bulb. A copy of a record, obtained 

 by the photo-thermograph, showing the arrival of a short "heat-wave" one summer's 

 afternoon. On the upper line note the rapid rise of 17 F. between i p.m. and 4 p.m.; and 

 the almost sudden drop of 10 just after 8 p.m. The lower line is a simultaneous record 

 from the "wet " bulb, and shows the effect of evaporation on the temperature. The great 

 departure of the upper trace from the lower one between 4 p.m. and 8 p.m. means that the 

 hot air was also very dry, much drier than was the air before and after that time. 



