'Sky' in the Bible

But He replied to them, “When it is evening, you say, ‘It will be fair weather, for the sky is red.’

And in the morning, ‘There will be a storm today, for the sky is red and threatening.’ Do you know how to discern the appearance of the sky, but cannot discern the signs of the times?

“But immediately after the tribulation of those days the sun will be darkened, and the moon will not give its light, and the stars will fall from the sky, and the powers of the heavens will be shaken.

And then the sign of the Son of Man will appear in the sky, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of the sky with power and great glory.

And He will send forth His angels with a great trumpet and they will gather together His elect from the four winds, from one end of the sky to the other.