Saturday, February 13, 2021
Many people say they have the most extraordinary sunset in the world. Today we are looking for an explanation for the appearance of the color range of the sunset and a few of the many effects that are currently occurring. Remember that sunlight is a mixture of colors. Even when the light changes half, for example when it goes from air to the water, it changes direction (refraction). We have all seen how rowing, when entering the water, seems to bend. Moreover, the light is spread and absorbed through the atmosphere. The biggest values of refraction and dispersion occur with the color blue and gradually decrease to the lowest value for red. This explains that the air is blue during the day. But what happens in sunset?
Let’s look, first color. In the afternoon the sunlight is delivered perpendicular, but in the sunset the light comes tangentially, it runs a longer path (30% more), it is more absorbed by the atmosphere and less intense. But please don’t think about looking in the sun with binoculars. Moreover, the sunlight is scattered by crossing the atmosphere. When the route is vertically vertical to spread almost all the blue and a bit the colors that follow. On the sunset, with the longest route, it can spread completely to yellow and, to our eye, the two colors that remain, orange and red reach us. These effects increase with pollutants that contribute to a spectacular sunset, but to serious environmental problems.
A second effect is that our star, on its sunset, loses its sfericity. It is an optical effect. On the horizon, the refraction shows us the highest sun than it actually is. A kind of mirroring. That is why, when we see the lower part of the sun hit the horizon, a mess is already hidden. In this optical effect, the lower part rises more than the top. That is why the end result is that of a bulb department through the soil and somewhat focused by the upper one. These distortions are modified with a thermal investment or a large hot surface. This happens when the sunset occurs in a lake or in the sea, if the water is hotter than the air above.
A third effect on sunset is the famous green beam, although it can be of other colors. It is a flash that only takes one or two seconds in favorable conditions. There are three versions. The most common is a green excerpt that appears in the upper part of the sun with the rest of intense red. Because the size of the green fragment is lower than the optical resolution of the vision, except in exceptional situations, the observation needs an optical instrument. Another version, when the last visible part of the West Sun becomes green. This can be seen with the naked eye. Finally, the green jet itself, rare, appears as a crushed emerald drop on the surface of the sea on the horizon.
