Temperature formulas (Heat Overlay): Difference between revisions

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Two temperature formulas are used in the calculation of the PET value:
* The atmospheric temperature [[#Atmospheric Temperature formula|T<sub>a</sub>]]
* The wet-bulb temperature<ref name="bulb" /> [[#Wet-bulb Temperature formula|T<sub>w</sub>]]
==Atmospheric Temperature formula==
==Atmospheric Temperature formula==
T<sub>a,t</sub> = T<sub>station,t</sub> + UHI<sub>max,t</sub> * f<sub>sun<sub>[t]<br>
<math>T_{a,t} = T_{station,t} + UHI_{max,t} \cdot f_{sun,t}</math>
where,
 
* T<sub>a<sub> is the calculated [[Temperature_atmosphere_result_type_(Heat_Overlay)|atmospheric temperature]] at time t;
where
* T<sub>station,t</sub> is the temperature measured at a weather station at time t;
* <math>T_{a,t}</math> is the calculated [[Temperature_atmosphere_result_type_(Heat_Overlay)|atmospheric temperature]] at time t;
* UHI<sub>max,t</sub> is the calculated [[UHI_formula_(Heat_Overlay)|Urban Heat Island]] effect at time t;
* <math>T_{station,t}</math> is the [[Hourly_temperature_(Heat_Overlay)|temperature]] measured at a weather station at time t;
* f<sub>sun<sub>[h] is the sun daily motion factor at time t;
* <math>UHI_{max,t}</math> is the calculated [[UHI_formula_(Heat_Overlay)|Urban Heat Island]] effect at time t;
* <math>f_{sun,t}</math> is the [[Sun_daily_motion_(Heat_Overlay)|sun daily motion factor]] at time t;
 
==Wet-bulb Temperature formula==
<math>T_{w,t} = T_{a,t} \cdot \arctan( 0.151977 \cdot \sqrt{\phi + 8.313659})+ \arctan (T_{a} + \phi) - \arctan(\phi - 1.676331) + 0.00391838 \cdot \phi^{\frac{3}{2}}  \arctan(0.023101 \cdot \phi) - 4.686935</math>
 
where:
* <math>T_{w,t}</math> is the calculated wet-bulb temperature;
* <math>T_{a,t}</math> is the calculated atmospheric temperature;
* <math>\phi</math> is the [[Sun_altitude_(Heat_Overlay)|sun altitude angle]];
* Constant values are sourced from the {{Heat DPRA Report}};
 
==See also==
<references>
<ref name="bulb">Wikipedia • Wet-bulb temperature • https://en.wikipedia.org/wiki/Wet-bulb_temperature • Last visited: 20-12-2019</ref>
</references>
{{Template:HeatOverlay_formula_nav}}

Latest revision as of 11:53, 13 September 2021

Two temperature formulas are used in the calculation of the PET value:

  • The atmospheric temperature Ta
  • The wet-bulb temperature[1] Tw

Atmospheric Temperature formula

where

  • is the calculated atmospheric temperature at time t;
  • is the temperature measured at a weather station at time t;
  • is the calculated Urban Heat Island effect at time t;
  • is the sun daily motion factor at time t;

Wet-bulb Temperature formula

where:

  • is the calculated wet-bulb temperature;
  • is the calculated atmospheric temperature;
  • is the sun altitude angle;
  • Constant values are sourced from the DPRA Heat stress report;

See also

  1. ↑ Wikipedia • Wet-bulb temperature • https://en.wikipedia.org/wiki/Wet-bulb_temperature • Last visited: 20-12-2019
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