Explanation:

The term "shimmering" refers to the visual effect that occurs when the air above the ground appears to be wavering or shimmering. It is most commonly seen on hot summer days when the sun is beating down on the ground and heating up the air just above it.

Causes of Shimmering:

There are two main causes of shimmering:

1. Refraction of Light - The air above the ground is not uniform in temperature, and as a result, it has different densities in different areas. When light passes through these areas, it is bent or refracted, which causes the shimmering effect.

2. Convection - As the air above the ground heats up, it rises and cooler air from higher up moves in to take its place. This movement of air causes distortions in the light that is passing through it, creating the shimmering effect.

Examples of Shimmering:

Shimmering can be seen in a variety of settings, including:

- On hot summer days, when the sun is beating down on the ground and heating up the air just above it.
- Over hot asphalt or concrete, where the heat radiating from the surface causes the air above it to shimmer.
- Above a barbecue or campfire, where the heat rising from the flames causes the air to shimmer.

Conclusion:

In conclusion, the term "shimmering" refers to the visual effect that occurs when the air above the ground appears to be wavering or shimmering. This effect is caused by the refraction of light and convection, and it is most commonly seen on hot summer days.