In this case, you will have the maximum visibility determined by the combination of the graphic and nominal range. The sun is shining, there are few clouds in the sky, and there are no smoke or pollution in the air. Let’s look at the range possible in different weather. Visibility varies, depending on the number of aerosols in the air (water droplets, ice crystals, dust, and more), as these reflect incoming light. Even if you are on a big tanker at sea, looking towards a tall lighthouse onshore, your range could be very small in certain conditions. Visibility at sea is also greatly affected by weather. However, you may be able to see the light of a 15-meter (50 feet) high lighthouse perched on a low rock from a distance of 23 kilometers (14 miles). Your graphic range may be 4.5 kilometers (2.8 miles) on a clear night, standing on the deck of your motorboat. So visibility is the combination of the graphic range and the nominal range. For example, a tall lighthouse on top of a cliff will be visible from farther away than a small motorboat. Your range will also be influenced by the size and height of the object you are looking at. So you will have greater visibility from the deck of a tanker than from the cockpit of a sailboat. This is limited by the curvature of the Earth and affected by the height at which your eyes are. What we usually call “visibility”, is the graphic range. You may be able to see the light from 11 kilometers (7 miles) or even 3 kilometers (2 miles) away, depending on the circumstances. It’s the distance from which you can see something. The graphic range, on the other hand, is much smaller. For example, the light of a lighthouse could have a 21-kilometer (13-mile) nominal range of visibility at night. The nominal range determines the maximum visibility of an object in the best possible conditions. There are two ranges of visibility: the nominal range and the graphic range. Visibility: Nominal range and graphic range However, things are actually a lot more complicated than that. This is the best possible visibility at sea you can have, if your eyes are six feet above sea level and the weather is great.

Generally, an average height person can see up to 4.5 kilometers (2.8 miles) at sea level.

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