Does soil release cold into the air during spring thaw?

Submitted by BustedLake t3_1215z0w in askscience

I have been a longtime basement tenant. Sometimes it seems like, during spring thaw periods, the air feels colder in the basement despite warmer temperatures above ground / outside. Is there any science at play re: frozen soil releasing cold temperatures at the ground / underground level? Or is it my imagination? Thank you for your time and consideration.

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PyrrhoTheSkeptic t1_jdossrz wrote

You have it backwards, though the feeling is the same. Cold things absorb heat. Cold is the absence of heat, and is not a thing in itself.

So, in a basement, if the walls and soil outside are cold, they will absorb heat that comes into the air, making the air cooler down there.

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CrustalTrudger t1_jdqabab wrote

To add to the clarification by /u/PyrrhoTheSkeptic that what you're describing is the absence of heat in the surrounding soil (and thus heat within your basement is "flowing" into the surrounding soil via conduction), neither soil or rock are great heat conductors (i.e., they generally have low thermal conductivity). What this means, is that it takes a while for the temperature of the soil/rock at even a shallow depth to change after a change in surface temperature. Observations suggest that if, for example, you consider either diurnal (i.e., day-night) or seasonal oscillations in temperature, the amplitude of these oscillations decrease exponentially with depth (e.g., Elias et al., 2004). In other words, even though the air temperature may be warm or cold (and oscillate between them), the soil temperature at a few meters down will be more constant. You can see in data of very shallow soil temperature (e.g., Holmes et al., 2008) that you do see things like diurnal temperature variation in the upper most few cm, but within >15-20 cm, the magnitude of diurnal temperature variations of the soil are extremely small.

It's worth noting that if you go deep enough (few 10s of meters) that the temperature of rocks ceases to be influenced by either diurnal or seasonal surface temperature variations and is instead controlled by the local geothermal gradient.

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mrWizzardx3 t1_jdqi6jp wrote

This is counterintuitive, but correct. During a phase change, energy is released and absorbed by the substance. For example, when water freezes it gives off energy to the surroundings. This is why orchards spray water on their fruit during a cold snap… the heat given off by the freezing water might be enough to save the fruit from freezing too. Similarly, when the water in the ground around your basement thaws, it pulls that energy from somewhere… and that could very well be the walls, floor, and air of your living space.

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