UHI formula (Heat Overlay): Difference between revisions
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The S is calculated as followed: | The S is calculated as followed: | ||
S = R<sub>avg</sub> / (C<sub>air</sub> * ρ<sub>air</sub>) | S = R<sub>avg</sub> / (C<sub>air</sub> * ρ<sub>air</sub>)<br> | ||
where, | |||
* R<sub>avg</sub> is the daily average radiation in W/m<sup>2</sup>hr<sup>-1</sup> | |||
Revision as of 13:16, 11 September 2019
The Urban heat island effect is calculated using the following formula:
UHImax = ( 2 - Svf - Fveg ) * ( S * (Tmax-Tmin)3 / U )-4
where:
- Svf is the calculated average sky view factor;
- Fveg is the calculated average vegetation fraction;
- S is
Analysis
The formula has two parts, the factor and the temperature effect:
UHImax = factor * temperature_effect
Factor
The factor is influenced by the sky view factor and the vegetation fraction, both ranging from 0 to 1. When both are low, i.e. barely any sky and no vegetation, the factor is near 2. When both are high, i.e. no surrounding buildings and a lot of vegetation, the factor is near 0.
Temperature effect
The S is calculated as followed:
S = Ravg / (Cair * ρair)
where,
- Ravg is the daily average radiation in W/m2hr-1