John
In daylight, air is always colder than soil; consequently, heat is transferred from the soil to the air, not vice versa."
if I go outside and stick a thermometer in my yard it will read 65 F even if the "air" temperature is 95 F
even if the "air" is 45 F the ground is 65 F
so the air is always colder must be incorrect.
stable ground temperatures is how geothermal cooling and heating works.
the thermal mass earth is greater than that of air because its density is greater than that of air.
heat moves into the earth from the air , it is the shear mass of the earth that allows this heat transfer to occur.
if you feel your desk with your hand it feels colder than the air
in the room , this is because the heat from your hand is moving / transfering into the desk because it has a higher thermal mass than your hand , just like the ground has a higher thermal mass than the air.
have you ever wondered why water pipes are underground?
it is because the ground stays warmer than the air in winter.
In simple terms, the second law is an expression of the fact that over time, ignoring the effects of self-gravity, differences in temperature, pressure, and density tend to even out in a physical system that is isolated from the outside world.
your hand is an observance of the second law , as you place your hand on your desk your hand feels the coldness of the desk , then your hand begins to warm as the heat from your hand transfers into the desk.
your hands temperature is equalizing with your desk temperature , the heat is flowing from hot to cold not vice versa.
