Meaning: This means that the expanse of space that can be seen from the earth is changing and becoming something else with less light. It's a way of describing what happens in the sky before it rains.
Choice of Words:Sky is the expanse of space that can be seen from the earth. Turns is to change or become something else. Darker means having less light.
Alternative Expressions
The sky is getting darker.
Meaning: This means that the sky is slowly becoming less bright, as if it's getting closer to night time or a storm is coming.
Choice of Words:Sky refers to the space above the Earth that we see. Is getting means gradually becoming something. Darker means less light or becoming less bright. When you put them together, "The sky is getting darker" describes a gradual change in the sky where it's becoming less bright.
The sky becomes dark.
Meaning: This means that the sky has changed to become less bright, as if it's night time or a storm has come.
Choice of Words:Sky refers to the space above the Earth that we see. Becomes means to change into something. Dark means having little or no light. When you put them together, "The sky becomes dark" describes a change in the sky where it becomes less bright.