Why do we not see a shadow of an airplane or a flying bird?

Explanation:
- Altitude: When an airplane or a bird is flying at a high altitude, the angle of the sun's rays hitting the object is more direct, resulting in a smaller or non-existent shadow being cast on the ground. This is because the shadow is cast directly below the object, making it difficult to see from the ground.
- Speed: Airplanes and birds are constantly moving when they are flying. This movement can make it challenging for a shadow to be visible on the ground as the object is continuously changing its position relative to the sun.
- Size of the object: The size of the object also plays a role in the visibility of its shadow. A small bird or airplane may cast a faint shadow that is not easily noticeable from the ground, especially if the object is far away.
- Atmospheric conditions: Atmospheric conditions such as clouds or haze can also affect the visibility of a shadow. If the sky is overcast or if there is a lot of dust and particles in the air, the shadow may be obscured or distorted, making it difficult to see.
- Distance: The distance between the object and the observer on the ground can also impact the visibility of the shadow. If the object is too far away, the shadow may be too faint to be seen clearly.
In conclusion, the combination of high altitude, speed, size of the object, atmospheric conditions, and distance from the observer all contribute to why we may not see a shadow of an airplane or a flying bird.