Here a few charts comparing the air temperature with the temperature near the soil surface when there`s snow cover (2/4-2/6) and no snow cover (3/12 and 3/13).

 The white tube in one the pictures is where the temperature sensor is located for the surface reading.

(harlans n o t 2 4 2014.jpg)

(harlans n o t 2 5 2014.jpg)

(harlans n o t 2 6 2014.jpg)

(harlans n o t 3 12 2014.jpg)

(harlans n o t 3 13 2014.jpg)

(h n ot 2 19 2014 11 inches deep 001.jpg)

(h n o t 3 15 2014 laid over residue.jpg)

harlans n o t 2 4 2014.jpg (26KB - 55 downloads)

harlans n o t 2 5 2014.jpg (26KB - 55 downloads)

harlans n o t 2 6 2014.jpg (27KB - 49 downloads)

harlans n o t 3 12 2014.jpg (24KB - 53 downloads)

harlans n o t 3 13 2014.jpg (29KB - 56 downloads)

h n ot 2 19 2014 11 inches deep 001.jpg (53KB - 58 downloads)

h n o t 3 15 2014 laid over residue.jpg (108KB - 47 downloads)