Temperature formulas (Heat Overlay): Difference between revisions
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==Wet-bulb Temperature formula== | ==Wet-bulb Temperature formula== | ||
T<sub>w</sub> = T<sub>a</sub> · atan( 0.151977 · (ϕ + 8.313659)<sup>0.5</sup>) + atan (T<sub>a</sub> + ϕ) - atan(ϕ - 1.676331) + 0.00391838 · ϕ<sup>3/2</sup> atan(0.023101 · ϕ) - 4.686935<br> | T<sub>w,t</sub> = T<sub>a,t</sub> · atan( 0.151977 · (ϕ + 8.313659)<sup>0.5</sup>) + atan (T<sub>a</sub> + ϕ) - atan(ϕ - 1.676331) + 0.00391838 · ϕ<sup>3/2</sup> atan(0.023101 · ϕ) - 4.686935<br>, | ||
where: | |||
* T<sub>w,t</sub> is the calculated wet-bulb temperature; | |||
* T<sub>a,t</sub> is the calculated atmospheric temperature; | |||
* ϕ 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] | ||
Revision as of 15:32, 11 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
Ta,t = Tstation,t + UHImax,t · fsun,t
where,
- Ta,t is the calculated atmospheric temperature at time t;
- Tstation,t is the temperature measured at a weather station at time t;
- UHImax,t is the calculated Urban Heat Island effect at time t;
- fsun,t is the sun daily motion factor at time t;
Wet-bulb Temperature formula
Tw,t = Ta,t · atan( 0.151977 · (ϕ + 8.313659)0.5) + atan (Ta + ϕ) - atan(ϕ - 1.676331) + 0.00391838 · ϕ3/2 atan(0.023101 · ϕ) - 4.686935
,
where:
- Tw,t is the calculated wet-bulb temperature;
- Ta,t is the calculated atmospheric temperature;
- ϕ is the sun altitude angle;