Hello all,

This came from another forum. I am attempting to calculate and generate entropy data based on EPW and create an hourly plot. I am wondering if this can be used in atmospheric science, meteorology, or weather forecasting. **(theoretical base)**.

Below are the two calculation/hypothesis methods:

****Method 1:**

Relationship between Enthalpy and Entropy:

**TΔs = Δh − vΔp**

where:

**T**is the temperature (k)**Δs**is the change in entropy**Δh**is the change in enthalpy**v**is the specific volume**Δp**is the change in pressure

In this method, the specific volume **v** and the pressure change **Δp** is ignored, which means the direct relationship between Enthalpy (H) and Temperature (T) is only considered. This can be simplified to:

**Δs = Δh/T**

To calculate the change in entropy ΔS:

Assuming **H** is the change in enthalpy per unit mass (kJ/kg), and the initial state has a change in enthalpy Δh=16.63 kJ/kg, with the initial state’s entropy being zero (reference state), it can be written as:

**ΔS = H/T**

****Method 2:**

In this method the specific volume **v** is ignored (assume = 1), **Δh** and **Δp** is done by substrate the value of previous hour.

Therefore:

**TΔs = Δh − 1 * Δp**

Please let me know what you thinks, and if it even make sense!

Entropy.gh (52.2 KB)