system
Given the following post, respond as if you're commenting on Reddit:
human
Why does heat cause visible waves through the air?
gpt
Warm air is less dense than cold air.  And different temperature masses of air have different indices (the plural of index) of refraction--they bend light by different amounts. So the air above a hot object is less dense, is rising because it is more buoyant, and bends light differently.  Naturally, light that must pass through that air to reach your eye will be distorted.