Mirages usually appear in which season?

Mirage, also known as mirage, is a natural phenomenon formed by refraction and total reflection of light, and its formation is closely related to weather situation, meteorological conditions, geographical location and geophysics. Mirages can be seen at sea or on land, and their characteristics are that they appear repeatedly at the same time and place.

Due to different densities, light will be refracted at the boundary of temperature gradient. The human brain thinks that light always travels in a straight line, but when it passes through the low-temperature and high-density atmosphere, it will be refracted downwards, so the distant buildings in the brain will be higher than the actual ones. In summer, most parts of the earth are rainy, coupled with strong sunlight in summer, thus forming a mirage.

Formation condition

In summer, the sun shines brightly in the desert and the sand is burnt. Because of the small specific heat of sand, the air temperature in the lower layer near the sand rises very high, while the air temperature in the upper layer is still very low. This forms an abnormal distribution of temperature. Due to thermal expansion and contraction, the density of hot air in the lower layer near the sand is low and the density of cold air in the upper layer is high, so the refractive index of air is small in the lower layer and large in the upper layer.

When the light reflected by a distant higher object enters the sparse air in the lower layer from the dense air in the upper layer, it will be refracted continuously, and its incident angle will gradually increase until it is equal to the critical angle. At this time, if people look against the reflected light, they will see the next slug. Because of the dark color of the pavement, asphalt pavement has strong absorption ability in the hot summer sun. It will also form the distribution characteristics of cold density at high altitude and hot density at low altitude, so it will also form low flying.

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