Mirages are natural phenomena in deserts and polar regions where the refraction of light by temperature differences creates the appearance of objects that aren’t actually there, and have confused many people throughout history.
A mirage is a phenomenon where something appears to be there when it’s not. However, a mirage is not an illusion or trick of the eye, but rather a phenomenon where the original object appears to be somewhere else due to temperature differences in the air layers. This is a fascinating topic in physics, and is a natural “optical illusion” caused by light refraction and density differences. Mirages aren’t just visual illusions, they’re the result of scientific laws in nature. A layer of cold air is denser and a layer of warm air is less dense. This difference in density changes the time it takes for light to travel through the air: the denser it is, the longer it takes. As light travels through the air, it bends as it crosses boundaries of different densities. This is why mirages can be easily observed in deserts and polar regions where there is a large temperature difference between the air at the surface and the air above it.
These natural phenomena have long provided people with mystical experiences. For example, people traveling through deserts in the past often saw mirages and mistook them for the appearance of oases or villages. This is an example of how visually realistic mirages can be. In the hot summer, the surface of the desert is easily heated by the sun, and the air at the surface is easily hotter than the air above it. Hot air is less dense than cooler air, and this difference in density causes light to refract. Imagine a tree above a desert. Some of the light from the top of the tree travels straight up and reaches our eyes, so we see an upright tree. However, some of that light travels downward, passing through a layer of dense air, where it continues to refract and travel back upward, while the light from the lower part of the tree continues to refract and travel further upward. Because of this change in position, the tree appears to us to be upside down. This is called the ‘downward mirage’. So, when viewed from a distance, you see the image of an upright tree and an upside-down tree underneath it at the same time.
Mirages also occur in very cold regions. The air at the snow-covered surface of the polar regions is always much colder than the air above it. The density of the cold air layer is greater, and the density of the warm air layer is less. This difference in density causes light to bend toward the denser surface and enter our eyes. This is why mountain peaks at the poles appear to be higher than they actually are. This phenomenon is called the “upward mirage”.
There are many different situations where mirages appear. For example, you can observe them at the beach. Near the coastline, when the ocean water is on the border of cool and warm weather, objects near the horizon can appear distorted. This often causes ships to appear to be floating in midair, or the shoreline to appear to be greatly deformed. On hot summer afternoons, the surface temperature can easily increase. When driving on a heated asphalt road, it can sometimes appear as if there are puddles of water on the road ahead. However, as you approach, the puddle soon disappears and another puddle appears some distance ahead. This happens because there is a temperature difference between the surface of the earth and the air above it, which causes light from the sky to be refracted and enter our eyes. On a spring day when the weather suddenly warms up, the heated air near the surface rises and falls, causing irregular density changes. These changes cause a difference in the refraction of light, which is what creates a haze. In this case, the position of the object doesn’t change, but because of the turbulence, the object appears to move in place.
