If you’ve ever lived in a house with a basement, or spent time in a cave, you are probably aware that the temperature underground
remains fairly constant regardless of what the air temperature is doing. Many times the basement is the warmest part
of the house in the winter, and the coolest in the summer. Old time root cellars took advantage of this
uniform temperature before air conditioners and central heat were common.
Obviously, fluctuations in the air temperature will
penetrate some distance into the ground.
How deep will they go? While this
question is fascinating all by itself, it has some practical implications, too.