Final answer:
The visible part of overlapped shingles is known as the exposure, which is the part exposed to weather and is an important aspect of roof construction.
Step-by-step explanation:
The visible part of overlapped shingles on a roof is called the exposure. This is the portion of the shingle that is exposed to the weather and is not covered by the next layer of shingles above it.
The exposure is carefully calculated to ensure it provides adequate protection against the elements while maximizing the use of the material.
The exposure length can vary depending on factors such as the type of shingle, the slope of the roof, and the specific roofing practices used.
An "exposure" is a single shutter cycle. For example, a long exposure refers to a single, long shutter cycle to gather enough dim light, whereas a multiple exposure involves a series of shutter cycles, effectively layering a series of photographs in one image. The accumulated photometric exposure (Hv) is the same so long as the total exposure time is the same.