This essay is part of my Advanced Mold Inspection Training course.
The picture attached shows visible signs of apparent mold around a skylight fitted to a sloped roof. The pattern of the mold suggests water intrusion caused by condensation on the inside of the skylight. This condensation is created when the outdoor temperature is cooler than the inside temperature making the air around the skylight have a higher relative humidity than the surrounding room air. Condensation forms and in this case the evidence suggests rivulets of moisture have run down the skylight well wall.
My next step in this mold inspection would be to collect a sample using an approved method and send to a laboratory for analysis.