Formation of a cumulus cloud street consisting of the species cumulus congestus of the radiatus variety. This formed as the Mistral wind gradually increased to strong at around 1245 CEST during maximum solar heating hence forming the photographed cloud streets moving along the wind. The weather sounding confirmed that the clouds had developed due to very steep lapse rate caused by the inflow a cool airmass moving over a warm ground heated by the Summer sunshine. An upper-level trough was still present and the primary cause of this cold airflow was an unseasonably strong high pressure over the UK directing a cold airmass via the Balkans and reaching our Islands from a NW direction following the isobar lines.