Formation of what appears like long parallel bands possibly due to passing aeroplanes and long dissipation. These form when the right conditions of temperature, pressure and humidity are present. The weather sounding showed very moist air at the upper reaches of the atmosphere but in a high pressure situation as the third thumbnail indicates. The photographed cloud in the first thumbnail is of exactly the same species as that in the main. However, one can note that the falling tendrils are very similar to mammatus. This happens when the formed ice crystals obtaining further water vapour from the surrounding environment become too heavy to remain aloft hence the ice crystals literally begin to fall from the sky. However falling ice crystals would melt and evaporate long before they reach the ground.