Fire appears to have no shadow because it emits light. Shadows are created when an object blocks light, causing a region of darkness to form behind it. However, fire produces its own light through a chemical reaction called combustion. The combustion process involves the rapid release of energy in the form of heat and light.
When a fire burns, it emits light in various wavelengths, including visible light. This light illuminates the surrounding area, making objects in its vicinity visible. Since fire itself is a source of light, it doesn't cast a distinct shadow because it is already producing and emitting light in all directions.
However, if there are objects near the fire that block or partially block the light emitted by the fire, they can cast shadows onto surfaces behind them. In such cases, the shadows will not be caused by the fire itself, but by the objects intercepting or obstructing the light emitted by the fire.
It's important to note that the absence of a shadow directly behind the fire doesn't mean that fire doesn't interact with light. Flames can certainly affect the way light interacts with objects and the surrounding environment, leading to various visual phenomena like shimmering, distortion, or changes in color.