Diffuse radiation formula (Heat Overlay): Difference between revisions

Revision as of 13:34, 20 September 2019

The diffuse radiation is an input parameter for the PET-formula

The diffuse radation Q_d at time t is calculated using the following formula:

$Q_{d,t}=Q_{gl,t}*f_{transmission,t}$

where,

$Q_{gl,t}$ is the amount of sun radiation at time t, measured at a weather station.
$f_{transmission,t}$ is the atmospheric transmission factor at time t.

The atmospheric transmission factor f_{transmission,t} is calculated as followed:

where τ_a is the atmospheric transmissivity. This is calculated as:
$\tau _{a}={\frac {Q_{gl,t}}{1367\cdot \sin(\phi _{t})}}$

where,

$Q_{gl,t}$ is the amount of sun radiation at time t, measured at a weather station.
$\phi _{t}$ is the sun altitude angle in ° at time t.

@@ Line 25: / Line 25: @@
 |}
 where τ<sub>a</sub> is the atmospheric transmissivity. This is calculated as:<br>
-τ<sub>a</sub>  = Q<sub>gl,t</sub> / (1367 * sin (φ<sub>t</sub>)) <br>
+<math>\tau_{a} = \frac{Q_{gl,t}}{1367 \cdot \sin(\phi_t)}</math>
 where,
-* Q<sub>gl,t</sub> is the amount of [[Hourly_radiation_(Heat_Overlay)|sun radiation]] at time t, measured at a weather station.
+* <math>Q_{gl,t}</math> is the amount of [[Hourly_radiation_(Heat_Overlay)|sun radiation]] at time t, measured at a weather station.
-* φ<sub>t</sub> is the [[Sun_altitude_(Heat_Overlay)|sun altitude angle]] in ° at time t.
+* <math>\phi_{t}</math> is the [[Sun_altitude_(Heat_Overlay)|sun altitude angle]] in ° at time t.
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