Thermal Vector

A continuous nocturnal draft was funneling upward against the exterior wall. Wedged between two iron balusters, a dry, curved leaf vibrated against the metal. I worked the brittle stem loose with both gloves, testing its balance along the central spine. Stepping to the outer edge of the railing, I held the fragment flat into the rising airflow and released my grip. The thermal current seized the surface instantly. It banked in a tight spiral, gaining rapid altitude before clearing the roofline into the open dark. Updraft velocity is sufficient to sustain lift. The exterior vertical airspace is navigable.