Why in a hot summer day, in a farmland air above the land is shimmering? Pls tell fast.

If we pass through a farmland during a hot summer day, we will see that the air above the soil is shimmering (shining with slightly shaking light). This happens as follows: The soil in the farmland contains some water on a hot summer day, this water of soil evaporates to form water vapour. The water vapour coming out of the soil reflects the sunlight irregularly due to which the air above the soil seems to shimmer.