Units

In order to make it easier to calculate formulae, the data is stored in the following formats:

• Temperatures are in degrees C
• Pressures are in hPa
• Times are stored in GMT
• Rainfall is in mm
• wind speed is stored in m/s
• Humidity is stored in percent
• The sampling interval is stored in minutes

Dewpoint Calculation

Our routines are derived from humidity information here. The formula we use is:
H = (log10(RH)-2.0)/0.4343+(17.62*t)/(243.12+t);
td = 243.12*H/(17.62-H);

Apparent Temperature Calculation

Our routines are based on information here. The formula we is is:
; e = Vapour Pressure (hPA)
e = rh / 100 x 6.105 x exp ( 17.27 x Ta / ( 237.7 + Ta ) )
; AT = apparent temperature
; ws = wind speed (m/s)
AT = Ta + 0.33 x e - 0.70 x ws ? 4.00