Before the test is started the undisturbed ground temperature must be determined.
They will remain active as long as the ground temperature is in the 40's.
The brightness of the heat signals told him that ground temperature must have been about freezing.
For one thing, it shows up in the ground temperature.
When ground temperatures become hot, they move into the low branches of shrubs or under vegetation.
He said the visibility, or lack of it, depended on the ground temperature where a person was standing.
Who knows how much the ground temperature drops here before dawn?
This was probably due to cold ground temperatures and snow accumulation.
Underground activity will go on until the ground temperature reaches about 40 degrees.
Weathered coal can also increase ground temperatures if it is left on the surface.
