About thermal admittance and difusivity
Hi Maja/Sandra,
I was wondering if you could elaborate on the second part of this question. All i can gather from that lecture and slides is that higher thermal diffusivity means the more rapid thermal heat change at depth. If we drain said soil it would warm rapidly..... I find the lecture posted does not give enough background or depth to this. Its just scratching the surface.....why does high thermal diffusivity result in large and rapid subsurface temperature response to surface temperature change? a short to the point answer would suffice. Thank you
Steven, thermal diffusivity (slides 21-22 of lecture #12) is driven in part by thermal conductivity (which increases exponentially in mineral soils with a small amount of soil moisture - see slide 15). Consider 2 soils (1 mineral and 1 organic) both of which are subject to a 1 degree increase in soil temperature - the mineral soil will rapidly conduct heat downwards due to it's high thermal conductivity. While it takes more energy to warm a "wet" mineral soil, once the temperature increases, that heat will be conducted down.