heatglare

Heatglare is a visual phenomenon caused by heat-induced air turbulence near the Earth's surface, often described as heat haze or heat shimmer. It arises when solar heating creates convection in the lower atmosphere, generating rapid, small-scale fluctuations in air temperature. Because the refractive index of air changes with temperature, these fluctuations bend light inconsistently along a line of sight, producing shimmering, waviness, and blurring of distant objects.

Heatglare is most noticeable on hot days over bright surfaces such as asphalt, concrete, or rooftops and is common along long sightlines such as highways, deserts, or urban streets. It can create mirages or a dancing, bending effect that reduces contrast and sharpness for visual observation, photography, and videography. The phenomenon is a form of atmospheric turbulence tied to near-surface heating, and its severity depends on surface temperature, wind speed, humidity, and the geometry between observer and target.

In practice, heatglare can degrade visibility and image quality, complicating tasks that require precision viewing or measurement at distance. While it shares underlying mechanisms with broader atmospheric turbulence, heatglare is specifically associated with surface heating and the resulting thermal plumes near the ground.

Mitigation is challenging in the field. Possible approaches include selecting times of day with less intense surface heating, increasing viewing elevation, or adjusting imaging and surveying techniques to accommodate the dynamic distortions introduced by near-surface air fluctuations.

See also: heat haze, mirage, atmospheric turbulence.