'Sky' in the Bible

Consider the birds of the sky, that they do not sow or reap or gather [produce] into barns, and your heavenly Father feeds them. Are you not worth more than they [are]?

And Jesus said to him, "Foxes have dens and birds of the sky [have] nests, but the Son of Man has no place to lay his head."

{It} is the smallest of all the seeds, but when it is grown it is larger than the garden herbs and becomes a tree, so that the birds of the sky come and nest in its branches."

So he answered [and] said to them, "[When] evening comes you say, '[It will be] fair weather because the sky is red,'

and early in the morning, 'Today [it will be] stormy weather, because the sky is red [and] darkening.' You know how to evaluate correctly the appearance of the sky, but you are not able [to evaluate] the signs of the times.