Valoilmiöt

Valoilmiöt are natural light phenomena that can be observed in the Earth's atmosphere. They are caused by the interaction of sunlight or moonlight with atmospheric particles, such as ice crystals or water droplets. These interactions can result in a variety of visual effects, often beautiful and sometimes spectacular.

One of the most common valoilmiöt is the rainbow. Rainbows are formed when sunlight is refracted and reflected by water droplets suspended in the air, typically after rain. Different wavelengths of light are bent at slightly different angles, causing the light to disperse into its constituent colors, creating the characteristic arc.

Another well-known valoilmiö is the halo. Halos are rings of light that appear around the sun or moon. They are typically caused by the refraction of light through ice crystals in cirrus clouds. The shape and appearance of the halo depend on the shape and orientation of the ice crystals. Sundogs, also known as parhelia, are a type of halo that appears as bright spots on either side of the sun.

Aurora borealis (Northern Lights) and aurora australis (Southern Lights) are perhaps the most dramatic valoilmiöt. These occur when charged particles from the sun collide with gases in the Earth's upper atmosphere, causing them to emit light. The colors of the aurora depend on the type of gas and the altitude at which the collision occurs. Other less common valoilmiöt include glories, iridescence, and light pillars.