Final answer:
A line that makes viewers feel like they are seeing a line when there isn't one is a implied line. Implied lines connect visual elements mentally to create the sense of a line and are an important compositional element in the arts to guide the viewer's eye and suggest movement.
Step-by-step explanation:
A line that gives viewers the impression that they are seeing a line where there is not a continuous mark is known as a implied line. An implied line is not actually drawn on the canvas but is rather suggested or formed in the mind, connecting visual cues or elements that suggest continuity. This can be seen through a series of points, the direction in which figures are looking, or shapes and edges that guide the eye.
Implied lines are a fundamental element in art and help to guide the viewer's gaze, create structure and organization within a composition, and suggest movement and tension. For instance, in Leonardo da Vinci's, though no explicit line is drawn, viewers can perceive implied lines connecting different elements of the painting, thus creating a sense of order and harmony.
In images like a lightning storm, no direct lines illustrate the path of the rain, but we can visually trace the line of water droplets fall, or the trajectory and movement implied by lighting. Implied lines can be created through contrasts, such as differing areas of color or lighting, which allow the viewer to mentally connect these areas and form a line.