Lysningsfænomener

Lysningsfænomener refers to the optical phenomena that occur when light interacts with atmospheric particles, such as ice crystals or water droplets. These phenomena are most commonly observed during twilight hours, particularly at sunrise and sunset, when the sun is below the horizon but its light is still scattered by the atmosphere.

One of the most well-known lysningsfænomener is the crepuscular ray. These are rays of sunlight that appear to radiate from a single point in the sky, typically the sun's position. This effect is caused by the scattering of sunlight by clouds, dust, or other particles in the atmosphere, which makes the light beams visible. The apparent convergence of these rays is an optical illusion, as they are in fact parallel.

Another related phenomenon is the Belt of Venus, also known as the pink band. This is a reddish or pinkish glow visible on the horizon opposite the sun during twilight. It is caused by the reddish light of the setting or rising sun being scattered by dust and aerosols in the upper atmosphere and then reflected by the Earth's surface onto the lower atmosphere.

The anti-twilight arch, or Earth's shadow, is also a lysningsfænomen. It is a dark blue band that appears on the eastern horizon just before sunrise or on the western horizon just after sunset. This band is the shadow of the Earth itself, cast upon the atmosphere by the sun.

These phenomena are not only visually striking but also provide insights into the composition and density of atmospheric particles at different altitudes. They are a beautiful demonstration of the interaction between light and the Earth's atmosphere.