When you view an object through hot air, its apparent position appears to fluctuate or waver.
Understanding the Phenomenon
Observing objects through layers of hot air, like the air above a hot road or pavement on a sunny day, often reveals a shimmering or wavy appearance. This effect alters where the object seems to be located.
Why Does the Position Waver?
The primary cause for this phenomenon is the refraction of light. Light travels at different speeds through media of varying densities and temperatures. Hot air is less dense than cooler air.
- Variations in Air: Hot air is typically turbulent, meaning it has pockets of air at slightly different temperatures and densities constantly moving and mixing. This creates variations in the air's physical condition.
- Light Refraction: As light rays from the object pass through these changing layers of air with varying densities, they bend or refract. The amount and direction of bending change rapidly as the air moves.
- Fluctuating View: Because the path of light is constantly shifting due to the turbulent, non-uniform hot air, the image you see of the object is slightly displaced from its true position. This rapid displacement makes the apparent position appear to fluctuate or waver.
This process is precisely why objects seen through hot air do not appear stationary; their apparent position is unstable and seems to move.
Practical Example
A common example is seeing objects in the distance over a hot asphalt road. The air just above the road surface is heated and less dense than the cooler air above it. As light from distant objects or the sky passes through this turbulent hot air layer, it refracts, causing the distorted, shimmering view and the perception that the objects' positions are wavering.
