Temperature formulas (Heat Overlay): Difference between revisions

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==Wet-bulb Temperature formula==
==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 · \phi^{\frac{3}{2}} \arctan(0.023101 \cdot \phi) - 4.686935</math>
<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>
<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:
where:
* T<sub>w,t</sub> is the calculated wet-bulb temperature;
* <math>T_{w,t}</math> is the calculated wet-bulb temperature;
* T<sub>a,t</sub> is the calculated atmospheric temperature;
* <math>T_{a,t}</math> is the calculated atmospheric temperature;
* ϕ is the [[Sun_altitude_(Heat_Overlay)|sun altitude angle]];
* <math>\phi</math> is the [[Sun_altitude_(Heat_Overlay)|sun altitude angle]];


==See also==
==See also==
* [https://en.wikipedia.org/wiki/Wet-bulb_temperature Wet-bulb temperature]
* [https://en.wikipedia.org/wiki/Wet-bulb_temperature Wet-bulb temperature]
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Revision as of 13:30, 20 September 2019

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

  • The atmospheric temperature Ta
  • The wet-bulb temperatur 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;

See also