* The speed of light is constant in a vacuum: This is a fundamental constant of nature, approximately 299,792,458 meters per second.
* Light slows down in matter: When light travels through matter, it interacts with the atoms and molecules, which causes it to slow down. This effect is greater in denser materials.
* Hot air is less dense: As air heats up, it expands, becoming less dense. This means there are fewer particles for the light to interact with.
Therefore, the speed of light in hot air is slightly faster than in cold air but still slower than in a vacuum.
However, the difference is very small. The speed of light in air is only about 0.03% slower than in a vacuum, and this difference is even smaller in hot air. For most practical purposes, you can consider the speed of light in air to be the same as in a vacuum.
