For shadows to be visible by the naked eye, they need light before they can appear. The presence of light would ensure the presence of shadows and vice versa.
A shadow is primarily that part of a lightened object (be it anything), which is shielded from oncoming light rays and hence is dark. This part is actually blocked by another object through which light can not pass. If the source of the light is small and puny, then the shadow would be sharply chiselled and well-pronounced and its shape would represent that of the object, which is actually producing the shadow. If the source of light is huge, then the shadow would be dark in the middle (a condition called umbra) and would be lighter and somewhat hazy from the sides (a condition called penumbra). That is why shadows which are cast by the sunshine always contain an umbra and penumbra primarily due to the enormous source of light that is producing them.
A shadow is primarily that part of a lightened object (be it anything), which is shielded from oncoming light rays and hence is dark. This part is actually blocked by another object through which light can not pass. If the source of the light is small and puny, then the shadow would be sharply chiselled and well-pronounced and its shape would represent that of the object, which is actually producing the shadow. If the source of light is huge, then the shadow would be dark in the middle (a condition called umbra) and would be lighter and somewhat hazy from the sides (a condition called penumbra). That is why shadows which are cast by the sunshine always contain an umbra and penumbra primarily due to the enormous source of light that is producing them.
