NSA/SKYRAD/C1 - NIP shaded by skyrad stand around local midnight

Around local midnight 9:30-10:30 GMT during summer clear sky the normal incidence 
pyranometer is shaded by the instrument stand.This causes the reading to be 0 W/m2. If cosine 
correction is applied for irradiance calulations this effect is negligible due to the low 
solar angle.

• NIP mean(nip_mean)
• NIP maximum(nip_max)
• NIP minimum(nip_min)
• NIP standard deviation(nip_sd)