Diffuse radiation formula (Heat Overlay): Difference between revisions
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|<math>\tau_a >= 0.7</math> | |<math>\tau_a >= 0.7</math> | ||
|} | |} | ||
where <math>\tau_a</math> is the atmospheric transmissivity. This is calculated as: | where <math>\tau_a</math> is the atmospheric transmissivity. This is calculated as: | ||
<math>\tau_{a} = \frac{Q_{gl,t}}{1367 \cdot \sin(\phi_t)}</math> | <math>\tau_{a} = \frac{Q_{gl,t}}{1367 \cdot \sin(\phi_t)}</math> | ||
Revision as of 14:19, 23 September 2019
The diffuse radiation is an input parameter for the PET-formula.
The diffuse radation Qd at time t is calculated using the following formula:
where,
- is the amount of sun radiation at time t, measured at a weather station.
- is the atmospheric transmission factor at time t.
Atmospheric transmission factor
The atmospheric transmission factor ftransmission,t is calculated as followed:
| ftransmission,t | Condition |
|---|---|
where is the atmospheric transmissivity. This is calculated as:
where,
- is the amount of sun radiation at time t, measured at a weather station.
- is the sun altitude angle in ° at time t.
