Figure 4: Determination of PBL height from thermodynamic values obtained by a VAISALA RS92 radiosonde. The radiosonde was launched at 12 UTC of the June 14th 2010 from the AWIPEV station of Ny Ålesund. In blue in the upper panel temperature and relative humidity while in the lower panel potential temperature and Richardson number. In dashed red the height of the PBL calculated for potential temperature with the Lapse Rate Method while the vertical green dashed lines on the fourth panel show the range of Richardson numbers between 0.21 and 0.25.