Visibility is the ability with the help of sight to distinguish objects located at a great distance from the observer. Visibility largely depends on the state of the air (transparency), weather, time of day and distance to the object.
Instructions
Step 1
The study of visibility is of paramount importance for transport where track, road signs and airstrips are used. The concept of "visibility" is widely used in topography, aerial photography to create military topographic maps.
Step 2
When conducting meteorological observations, atmospheric visibility is constantly analyzed for more accurate weather forecast. However, visibility does not need to be determined visually. It is determined from the map based on the mutual visibility of certain points, between which there may be obstacles that block the object from the view of the observer.
Step 3
In this case, visibility will depend on the observation height and the presence of local objects that prevent this. If the area or area to be surveyed is small and there are few local objects restricting visibility, its level may well be assessed by eye.
Step 4
In the case when individual objects are not visible, special calculations and constructions are made on the map, as a result of which the mutual visibility of terrain points and zones (fields) of invisibility is determined.
Step 5
Invisibility fields are terrain areas that are not visible from the observation point. Their boundaries, depending on the task at hand, can be determined both by eye and by the method of constructing terrain profiles.
Step 6
The quality of visibility is significantly affected by the transparency coefficient of atmospheric air. Here, for example, is how the transparency of air is measured when a ray of light passes through it. For this, the amount of light remaining after passing one kilometer of the atmosphere must be divided by the amount of light that was before the beginning of the passage.
Step 7
To improve the visibility of objects with small angular dimensions, you can use binoculars with additional accessories - red glass or an infrared device.
Step 8
A more modern method, for example, radar, allows observation and photography in the complete absence of visibility - in the dark, dense fog or cloudy sky.
