Many cumuliform towers in this altocumulus radiatus cloud due to the arrival of an upper-level trough signified by falling freezing levels as per third thumbnail. Such clouds normally indicate that a thunderstorm is brewing up and in this case, it did not miss as the first thumbnail sent to me by Andrea Galea show a lightning strike from a mid-level thunderstorm, the cloud being known as cumulonimbus altocumulogenitus. The second thumbnail is the weather sounding showing an unstable moist layer between 5.3km and 12.5km probably the base and top of the cumulonimbus in the first thumbnail. Little rain was observed from this thunderstorm as most of it evaporated before reaching the ground without causing a heat burst.