July 9, 1915] 



SCIENCE 



65 



rainfall of Great Britain.* In winter (Decem- 

 ber, January and February) the highest rain- 

 fall percentages are found in the southwest 

 portions of the British Isles; for there, the 

 comparatively warm, moist ocean winds are 

 cooled on reaching land. In spring, with the 

 rise of land temperature relative to that of the 

 ocean, there is generally deficient rainfall, the 

 highest percentages occurring in the east. 

 For the summer quarter, the eastern percent- 

 ages rise to more than 30 locally while those 

 in the west remain below 25. In autumn, the 

 rainfall exceeds 30 per cent, of the annual 

 total on the coasts of England and Scotland 

 while the maximum is less intense in Ireland. 

 Such maps, free from the confusing details of 

 the actual rainfall distribution, are well fitted 

 for exhibiting the seasonal rainfall variations. 



Tharmal Anomalies. — Of two methods of 

 indicating thermal anomalies, the first, and 

 that most generally used, is to construct iso- 

 nomalous lines which show the difference be- 

 tween the temperature of a place and the mean 

 for its latitude — no account being taken of 

 the relative amounts of land and water. In the 

 Scottish Geographical Magazine, July, 1914 

 (pp. 356-363), Mr. B. 0. Wallis has presented 

 apparently the first monthly maps of thermal 

 anomalies of the world. The negative anom- 

 alies of the continents in winter become posi- 

 tive in summer, while the positive anomalies 

 of the oceans in winter change to negative. 

 As the northern hemisphere summer ap- 

 proaches, there is a weakening of anomalies 

 throughout the world, a feature due to the 

 unequal distribution of land in the two hemi- 

 spheres. 



The other method of computing thermal 

 anomalies is based on the difference between 

 the temperature of a place and the tempera- 

 ture its latitude would have if the hemisphere 

 were wholly land (if the place is on land) or 

 wholly water (if the place is marine in loca- 

 tion). These anomalies Mr. J. Liznar calls 

 " true thermal anomalies. ''= Thus such figures 



4 ' ' Isomeric Rainfall Maps of the British Isles, ' ' 

 Quart. Jour. Boy. Meteorological Soc, January, 

 1915, pp. 1^4. 



5 Meteorological Zeitsclir., February, 1915, pp. 

 69-73. 



give a true measure of the degree of land or 

 ocean influence, but do not necessarily show 

 the difference in temperature between one place 

 and another in the same latitude. The accom- 

 panying table indicates the sea level tempera- 

 ture of the different latitudes of land and 

 water hemispheres: 



Land in any latitude is generally colder 

 than if the earth were entirely land. The ex- 

 ceptions are Europe, North Asia south to 60° 

 and western North America. At 70° N., 

 Greenland has a great positive anomaly of 

 1Y.3° 0. and the northwest coast of Norway 

 one of 22.1° C. The greatest negative anom- 

 alies are on land near the equator. The oceans 

 are mostly too warm for the latitude but the 

 anomalies are smaller than those on land. 

 Areas of negative anomalies are the south 

 Atlantic and south Indian oceans, and the 

 west coasts of North and South America. The 

 anomalies show clearly the transportation of 

 warmth by air and water. 



Climatic Profiles. — So many elements are 

 now shovm on separate climatic maps that it 

 is difficult to get general impressions of cli- 

 mates. Dr. K. Mahler^ has proposed the use 

 of climatic profiles as a remedy. To illus- 

 trate he has chosen three profiles in India. 

 Curves of mean temperature, air pressure, pre- 

 cipitation, cloudiness, relative humidity and 

 vapor pressure are placed one above the other 

 over a profile of land relief. In such a single 

 picture the fluctuations of the climatic means 

 are easy to determine and compare. Dr. 

 Mahler suggests (as did Henry Gannett in 

 1902, Monthly Weather Review, April, 1902) 

 the establishment of lines of observatories 



6 Verein f. Erdkunde, Dresden, Mitteilungen bd. 

 2, pp. 745-48; 3 pi., 1913. 



