Basic shapes, forms, shadows and reflections

What are the difficulties in separating cast shadow from reflected light and shade ?

If there are more than one light sources the clear shadow of the object may be obscured and/or altered, also lighter or darker without no set rules you must rely on your pure perception when painting or drawing in daylight. I did my studies in the night using only one light source except for the last image of stable composition which was done in natural day light. However even then the dominating light source was the window behind the objects. In the following image difference between cast shadow and reflected shadow has been illustrated clearly.

What is the difference between shade and shadow ?

shadow: I. Comparative darkness. 1. a. Comparative darkness, esp. that caused by interception of light; a tract of partial darkness produced by a body intercepting the direct rays of the sun or other luminary.

shade: I. Comparative darkness. 1 a. Partial or comparative darkness; absence of complete illumination; esp. the comparative darkness caused by a more or less opaque object intercepting the direct rays of the sun or other luminary.

Used in the sense of “comparative darkness,” the words are sometimes, but not always interchangeable.

Shade is what one seeks on a hot sunny day. We sit or walk in the shade. Plants that do well in the shade are called shade-loving plants.

Shadow usually refers to a shape cast by an object that blocks the sun. A person casts a shadow in the shape of the human body.

REFLECTIONS-SHADOW-LIGHT-9.

The reflected shadow and light follows the contours of the objects. How have you shown this in your drawing ?

IN stable composition the reflected lights and shadows were difficult to perceive as the dominating light was coming from behind the objects. Theory of the reflected shadow, which is in above apple picture the shadow of the apple on the ground reflected back into the apple as the round dark area shows in the apple, it is combined with the reflection of the white ground and thus is lighter in shade than the shadow itself.  Darkest area of the shadow called “terminator” is further away from the object where there is no reflections of the ground bouncing back to the ground. Note also how the reflected light on the right side of apple creates a halo around reflected shadow. The upper side of apple on the right is in shade and its value is the same as the reflected shadow, I dont know if its stable rule of thumb in theory. The black box with number 4 is how dark the terminator shadows is at furthers point in comparison.