Diffuse radiation formula (Heat Overlay): Difference between revisions
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The diffuse radiation is an input parameter for the [[PET_formulas_(Heat_Overlay)|PET-formula]] | The diffuse radiation is an input parameter for the [[PET_formulas_(Heat_Overlay)|PET-formula]]. | ||
The diffuse radation Q<sub>d</sub> at time t is calculated using the following formula: | The diffuse radation Q<sub>d</sub> at time t is calculated using the following formula: | ||
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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> | ||
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* <math>Q_{gl,t}</math> 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. | ||
* <math>\phi_{t}</math> 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. | ||
* <math>1367</math> is sourced from the {{Heat DPRA Report}}. | |||
{{Template:HeatOverlay_formula_nav}} | {{Template:HeatOverlay_formula_nav}} | ||
Latest revision as of 11:52, 13 September 2021
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.
- Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle f_{transmission,t}} is the atmospheric transmission factor at time t.
Atmospheric transmission factor
The atmospheric transmission factor ftransmission,t is calculated as followed:
| ftransmission,t | Condition |
|---|---|
| Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 1} | Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \tau_a < 0.3} |
| Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 1.6 - 2 \cdot \tau_a} | Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 0.3 < \tau_a < 0.7} |
| Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 0.2} | Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \tau_a >= 0.7} |
where Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \tau_a} is the atmospheric transmissivity. This is calculated as:
Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \tau_{a} = \frac{Q_{gl,t}}{1367 \cdot \sin(\phi_t)}}
where,
- Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle Q_{gl,t}} is the amount of sun radiation at time t, measured at a weather station.
- Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \phi_{t}} is the sun altitude angle in ° at time t.
- Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 1367} is sourced from the DPRA Heat stress report.
