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The moon has it's shadow like a cone shape (Figure (1)). It is called shadow cone. If the shadow cone reaches the earth, a total solar eclipse can be seen. The dark shadow on the earth's ground ( umbra ) can be seen from artificial satelites. Observers on the ground also can see the shadow cone that changes brightness of the atmosphere into darkness.
Figure (1)
From a few minutes before totality, the observers will see shadow cone is approaching in a very high speed from western sky. The western sky becomes dark, and the darkness is approaching the observer. Since the moon is going around the earth from west to east, and the speed is much faster than the earth's rotation speed, the shadow on the ground moves from west to east in a very high speed.
At a total eclipse that occurs in the morning, if an observer is watching the sun, the shadow cone comes from his back, since the sun is in the eastern sky. If the observer wants to see the shadow cone, he/she has to see the western sky, instead of seeing diamond ring.
After the totality, the shadow cone is going away eastern sky, it is also seen for a few minutes.
The shadow cone can be seen more clearly at a total eclipse that occurs in a low altitude than a high altitude in the sky, since the shadow cone passes long through the atmosphere.
