Diffuse radiation formula (Heat Overlay): Difference between revisions

Revision as of 13:36, 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 $\tau _{a}$ 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 15: / Line 15: @@
 !Condition
 |-
-|1
+|<math>1</math>
-|τ<sub>a</sub> <= 0.3
+|<math>\tau_a < 0.3</math>
 |-
-|1.6-2* τ<sub>a</sub>
+|<math>1.6 - 2 \cdot \tau_a</math>
-|0.3 < τ<sub>a</sub> < 0.7
+|<math>0.3 < \tau_a  < 0.7</math>
 |-
-|0.2
+|<math>0.2</math>
-| τ<sub>a</sub> >=0.7
+|<math>\tau_a >= 0.7</math>
 |}
-where τ<sub>a</sub> is the atmospheric transmissivity. This is calculated as:<br>
+where <math>\tau_a</math> is the atmospheric transmissivity. This is calculated as:<br>
 <math>\tau_{a} = \frac{Q_{gl,t}}{1367 \cdot \sin(\phi_t)}</math>