All these conditions are illustrated in Figure 3-5 for the variation of temperature over 1 day at New York/John F. Ke., on the 1st of June.

When diurnal temperature and relative humidity fluctuations have a low impact on the studied system, the Filter diurnal variation checkbox can be selected to smooth out the diurnal fluctuations. This is illustrated in Figure 3-6 showing the variation of temperature over 1 month at New York/John F. Ke.,

Here, ΔTwind (SI unit: K) is an additive correction applied to 〈Tstation〉, defined as

where ΔTws,station (SI unit: K) and ΔTwd,station (SI unit: K) are, respectively, the maximal variations of observed values of temperature correlated with a set of wind speed and direction observed values.

The heating and cooling wind correlations are illustrated in Figure 3-7 for the variation of temperature over 1 day, at New York/John F. Ke., on the 1st of June.

All these conditions are illustrated in Figure 3-8 for the variation of the dew-point temperature over 1 year at New York/John F. Ke.

All these conditions are illustrated in Figure 3-9 for the variation of the wind speed over 1 year at New York/John F. Ke.

where pstation (SI unit: Pa) is the observed value of absolute pressure at the station. Only a single value is available, so this data does not vary with time.

The relative humidity ϕamb (dimensionless) is computed from the temperature Tamb and the dew-point temperature DPTamb with the following relation:

where psat(Tamb) is the saturation pressure of vapor at Tamb. See Relative Humidity for more details.

As the diurnal variation of temperature is available, the diurnal fluctuations of relative humidity can also be computed with the Filter diurnal variation checkbox cleared, as illustrated in Figure 3-10 for New York/John F. Ke, on the 1st of June, for different ambient conditions.

Several conditions of relative humidity can be obtained from the selection of conditions for the temperature and dew-point temperature. The relative humidity can therefore exceed 1, as the red curve in Figure 3-10 shows.

The moisture content xvap,amb (dimensionless) is computed from the temperature Tamb, the absolute pressure pamb, and the relative humidity ϕamb with the following relation:

where psat(Tamb) is the saturation pressure of vapor at Tamb, and Mv and Ma are the molar masses of water vapor and dry air. See Moisture Content for more details.

With clear sky conditions, the noon solar irradiance is essentially provided by the beam normal irradiance, coming directly from the sun. However, the diffuse horizontal irradiance may be also considered. The sum of direct and diffuse solar irradiances is the ambient solar irradiance Is, amb (SI unit: W/m3), defined by:

where Isn,station (SI unit: W/m3) and Ish,station (SI unit: W/m3) are respectively the observed values of the clear sky noon beam normal and horizontal diffuse solar irradiances.

Figure 3-11 illustrates the evolution of ambient solar irradiance for New York/John F. Ke, over the year.