I'd like to offer an addition, which was originally posted as a comment but requested to be turned into an answer by OP.
As explained in the other two answers, iste, ille and hic are used to refer back to the items of a previous enumeration. In that sense, "the former ... the latter" is a perfectly acceptable translation. However, in your example this sounds a bit formal:
There is nothing, but the sea and air.
The latter swollen with clouds and the former threatening with waves...
In addition, as C. M. Weimer remarks:
[...] using "the latter...the former" in English actually emphasizes the abnormality of the former, while in Latin there is no such connotation.
In this case, it is clear which of "swollen with clouds" and "theathening with waves" refers to "sea" and which one refers to "air", so you could simply go with the more general "one / the other":
There is nothing, but the sea and air.
One swollen with clouds, the other threatening with waves...
This preserves the neutrality of the Latin formulation and sounds much more natural to me, at the expense of a less literal translation (which may or may not be what you are after).
You could even go for an even more free interpretation, with something like
There is nothing but the sea, threatening with waves, and air, swollen with clouds.
Although this is probably easiest to understand and arguably the most natural way to state it in English, it loses the chiasmus from the original text.