A shadow is formed where light is 'missing'.
Shadows Formed Outside - from sunlight or moonlight
On a sunny day, most of the light is coming
directly from the sun, but some of it is coming as blue scattered light
coming from the sky.
This hits you at all angles as it comes from all
directions.
Therefore, if you stand in front of the sun, the sun's light
is blocked, but your shadow still recieves light from the rest of the
sky, and you can still see the shadowed ground.
On a cloudy day, the
light is completely diffuse, not coming from anywhere in particular,
and you don't cast much of a shadow at all.
Now try some questions on this topic. Click the graphic to go to them.
LOJ (June 2001) - revised 2017