168 
H. MØLHOLM HANSEN 
maximum and minimum will take place at the different depths. 
Thus the temperature minimum in the lower strata will only occur 
simultaneously. with the temperature maximum at the surface, and 
reversely. 
The daily and annual mean temperature of the surface of the 
earth is higher than that of the air, just as the daily and annual 
amplitude is higher for the surface than for the air. 
TABLE 33. 
The annual Rise of Temperature 
in Soils with or without Vegetation or Snow Covering at Pawlowsk 
(Russia.) The figures give the mean values of a period of 5 years, 
189195, After H. Wild 1897: p: 7. 
1oW covering cm .. 
OUdS Fic te eee 
ir temperature C° 
atural external surface . 
indy surface 00em.... 
+ 40 
= ol) 
+160 
» 
» 
» 
November 
egetation or snow covered 
surface 0.0 cm 
— 40 
= 
3 me 
E Si 
vo a | 
2 a 
A ler) 
| 2 ie 
| 16 31 
8.5 8.3 | 
+674 |=-10.2 
6 | 
6.6 | 10.4 | 
206 
OT 9 
3.814.290 | 
I=-10.0 | 
7A | 
10.3 
9.6 
6.4 | 
2.7 
1.2 
1.4 
0.8 | 
1570) 
3.0 | 
+45 
143.5 | 
—-2.4 
Ha) 
0.8 
—-0.7 
0.7 
1.5 
2.6 | 
April 
> 
©o 
—— 
| 
© > a 2 2 | 
s|ı5:| | s/s] 
>.) 7 SEEREN 
Nn || 
» » » » » | 
6.1| 6.6| 6.6! 70|7.6| 
13.4 | 15.9 | 13.8| 8.7 4.0 
17.4 | 19.4|15.7| 92135] 
| 
16.7 | 18.91 15.5! 9.0! 3.6| 
13.3 | 16.7 | 15.2| 9.8|5.4| 
10,1 | 14.1 | 13.9 | 10.3 | 6.9] 
6.2 | 10.0 | 11.3 | 10.3 | 8.2) 
Lo) 
14.7| 17.0! 14 2 |. 9.0/4.2] 
11.6 | 14.6 | 14.7 111 | 7.3 
9.7 |12.6 | 13.5 | 1121023 
7.5 10.0 11.6 | 11.0} 9.1) 
i 
D —— 
The facts described above apply to bare homogeneous sandy soil, 
as invesligated by H. Wild at Pawlowsk, ef. table 33. 
If, on the 
other hand, the surface is clothed with a natural vegetation or 
covered with snow, a case likewise investigated by H. Wild in the 
same locality and shown in table 33, the facts will be otherwise. 
A bare sandy surface has a mean annual temperature of 4.0° with 
an annual amplitude of 29.2, a natural surface has a mean annual 
temperature of 3.6° and an annual amplitude of 29.2. 
The surface 
under snow and vegetation, on the other hand, has a mean annual 
