Breakup of a nocturnal temperature inversion in the Dischma Valley during DISKUS.

The nocturnal potential temperature inversion in Switzerland's Dischma Valley on 11 August 1980 was destroyed during a 4 1/2-h period following sunrise. The temperature inversion breakup was accomplished primarily by descent of the inversion top rather than upward growth of a convection boundary layer from the valley floor. The thermodynamic model of Whiteman and Mc-Kee, as extended with Steinacker's concept of valley area-height relationships, simulated inversion breakup well when sensible heat flux was assumed to be about 6% of the extraterrestrial solar flux. Observations in the valley support this value of sensible heat flux, which is lower than values observed in the drier Colorado valleys where the model was initially tested. (IFU)