1919-20.] Effect of Weather Changes on Soil Temperatures. 73 
provides a complete protection for the surface from very large variation of 
temperature above the snow surface. This is well shown in Table XII, 
which gives the temperature of the air above the snow, the soil surface, 
and the 4-inch and 8-inch depths during the severe snow and subsequent 
frost of November 12-16, 1919. During the whole period the surface 
of the soil remained unfrozen, though the air temperature over the snow 
fell to — 15° C. on one night, and averaged — 8° C. over the whole 
period ; the 4-inch temperature fell OS 0 C., and the 8-inch temperature 
0’5° C., while the snow was on the ground and before the rain came on 
November 17. 
Table XII. — Fluctuations op Underground Temperature during Lying Snow. 
Date and Hour. 
Air over 
Snow. 
Soil 
Surface 
under 
Snow. 
4-inch 
Depth. 
8-inch 
Depth. 
Depth of Snow 
lying. 
1919. | 
Nov. 12 1 
f 6 a.m. 
I noon. 
1 6 p.m. 
1 midnight. 
- 0-4° C, 
- 0-4° C. 
- 0-4° C. 
- 0-6° C. 
do' do 
O 0 o o 
O O O O 
6 6 6 6 
1-1° 0. 
1-0° C. 
1-0° c. 
1-0° c. 
2-1° C. 
2*1° C. 
2*1° C. 
2T° C. 
1 Snow ceased 8 
l p.m., lying 6 j 
| inches deep. 
Nov. 13 | 
( 6 a.m. 
noon, 
j 6 p.m. 
1 midnight. 
- 8*0° C. 
- 2-8° C. 
- 10-6° C. 
- 13-6° C. 
o o o o 
6 6 6 6 
o o o o 
poop 
1-0° c. 
1.0° c. 
1-0° c. 
1-0° c. 
2T° C. 
2-1° C. 
2.1° C. 
2T° C. 
j- 4 inches deep. | 
Nov. 14 j 
( 6 a.m. 
I noon. 
J 6 p.m. 
t midnight. 
- 15-0° C. 
i - 8-6° C. 
- 9-6° 0. 
- 7*7° C. 
0*0° c. 
0-0° C. 
1 0 0° c. 
i 0*0° c. 
1 
1-0° c. 
1*0° G. 
1*0° c. 
| 1-0° c. 
2-1° C. 
2T° C. 
2T° C. 
2-1° C. 
| 
j- 3 inches deep. 
J 
Nov. 15 j 
r 6 a.m. 
1 noon. 
6 p.m. 
1 midnight. 
-13-7° C. 
- 4*6° C. 
- 6-5° C. 
- 9-5° C. 
o o o o 
6 6 6 6 
O O O 0 
p p p p 
0-9° C. 
0-9° C. 
0-9° C. 
0-9° C. 
2-0° C. 
1-8° C. 
1-8° C. 
1-8° C. 
| 2f inches deep, j 
Nov. 16 j 
r 6 a.m. 
1 noon. 
6 p.m. 
i midnight. 
- 7-0° C. 
- T6° C. 
o-o° U. 
o-o° 0. 
0-0° c. 
o-o° c. 
o-o° c. 
o-o° c. 
0-8° C. 1 
0*8° C. 
0-8° C. 1 
0-7° C. i 
I 
1-7° G. 
1-7° G. 
1*7° C. 
1-6° C. 
| 1 2| inches deep, j 
J 
| Nov. 47 
1 
noon. 
7-o° c. 
0-4° C. 
0-5° C. 
1-4° C. 
All melted. 
1 
At 7 a.m. on November 14, 1919, when the air temperature was — 15° C. 
and the 4-inch depth temperature was 1° C., the soil surface was exposed 
and found to be unfrozen. Thus the heat conducted from the surface of 
the soil through the snow must have been balanced by the heat conducted 
to the surface from the 4-inch depth. 
