962 EXPERIMENT STATION RECORD. 



In conclnsioTi, it must not be forgotten that variations in weather are 

 accompanied by similar v^ariations in soil temperature. It is not pos- 

 sible to formulate general laws on this subject, because the relation- 

 ships are not only very com])licated in their nature but are entirely 

 local in character. In as far as it is possible to trace the connection 

 between climate and soil temperature in a particular case, it has been 

 done by K. Singer for the climate of the south Bavarian plain.^ The 

 results of this investigation may serve to show the conditions con- 

 cerned and are therefore inserted below. 



In the mild winter months, during which the precipitation is plenti- 

 ful, there is no particular rise in temperature compared with the nor- 

 mal, but rather a fall in the soil temperature, especially in the deeper 

 layers. Mild and dry winters have a ten<Iency to cause the tempera- 

 ture to rise above the normal. The tempei ature of the soil during a 

 winter of alternate frost and thaw, of which the average temperature 

 is below the normal, shows a tendency to siuk unless it is already very 

 low. In the same way, when hard frost follows mild and wet weather 

 in early winter even a covering of snow can prevent only to a slight 

 extent the general lowering of the soil temperature. On the other 

 hand, during a long and severe winter, in which the snow comes to stay 

 in December, the variation of the soil temperature is either confined to 

 the nppor layers or does not occur at all. 



A warm spring with, as is usual, a considerable amount of precipita- 

 tion, causes a decided (relative) rise in the soil temperature. When a 

 cold winter with much precipitation is followed immediately by a warm 

 spring, the temperature of only the upper layer rises, while that of the 

 lower layers may fall still further below the normal. In case of nnich 

 precipitation the soil temperatures remain unchanged comi)ared with 

 the normal during tiie different spring months. A cold spring, which 

 is generally accompanied by much snow, is associated, as a rule, with a 

 decided lowering of the soil temperature, even to great depths compared 

 with the normal. When the spring weather is cold and dry the relative 

 lowering of tlie soil temperature is generally slight, if it has not been 

 immediately preceded by periods of particularly large precipitation. 



A warm summer is always accompanied by a high soil temperature 

 or a rise. The rise is all the more noticeable when a large amount of 

 precipitation accompanies the high temperature of the air or imme- 

 diately precedes it. The rise in soil temperature is not much above the 

 normal during the warm and dry summer months. The lowering of 

 temperature always induced by a cool summer does not reach to great 

 depths, scarcely to 4 meters. Those months in which this relative low- 

 ering of temperature could be detected down to 6 meters were all very 

 wet. 



A warm autumn causes, with few exceptions, a relative rise in the 

 soil temperature. This rise is slight, and may even be changed to a fall 



•Beobachtungen der meteorologischen Statiouen im Konigreich Bayern, 11. 



