Temperature formulas (Heat Overlay)

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

• The atmospheric temperature T_a
• The wet-bulb temperatur T_w

Atmospheric Temperature formula

T_a,t = T_station,t + UHI_max,t · f_sun,t
where,

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

Wet-bulb Temperature formula

T_w = T_a · atan( 0.151977 · (ϕ + 8.313659)^0.5) + atan (T_a + ϕ) - atan(ϕ - 1.676331) + 0.00391838 · ϕ^3/2 atan(0.023101 · ϕ) - 4.686935

See also

• Wet-bulb temperature