Question

Soil heat flux is equal to

• A. \(\frac{dT}{dz}\)
• B. \(K \frac{dz}{dz}\)
• C. \(-K \frac{dT}{dz}\)
• D. \(\frac{dz}{dT}\)

Hint:

Fourier's law: \(G = -K \frac{dT}{dz}\).
Heat flows from warmer to cooler regions.
The negative sign accounts for the direction of heat flow.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This question tests knowledge of the formula for soil heat flux.

Step 2: Key Formula or Approach:
Soil heat flux is governed by Fourier's law of heat conduction.
The formula is: \(G = -K \frac{dT}{dz}\).

Step 3: Detailed Explanation:
In Fourier's law:
- \(G\) is soil heat flux (W m$^{-2}$).
- \(K\) is thermal conductivity (W m$^{-1}$ K$^{-1}$).
- \(\frac{dT}{dz}\) is the temperature gradient.
The negative sign indicates that heat flows from warmer to cooler regions (opposite to the temperature gradient).
Thus, soil heat flux is \(-K \frac{dT}{dz}\).
Final Answer:
Thus, soil heat flux is equal to \(-K \frac{dT}{dz}\), which corresponds to option (C).
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