St. Thomas must have implicitly believed the earth was flat with a firmament above it, etc. Because after all, what direction is "heaven" from a globe earth? Towards a specific star? Give me a break.

The physicist proves the earth to be round by one means, the astronomer by another: for the latter proves this by means of mathematics, e. g. by the shapes of eclipses, or something of the sort; while the former proves it by means of physics, e. g. by the movement of heavy bodies towards the center, and so forth.

Ia IIae, Q. 54, Art. 2, ad 2um

all the fountains of the great deep were broken up, and the flood gates of heaven were opened: [12] And the rain fell upon the earth

The fountains also of the deep, and the flood gates of heaven were shut up, and the rain from heaven was restrained.

Here is what St. Thomas Aquinas says in the Summa:

He also held the common belief in his time that the Pelican tore its own flesh and fed it to its young. St. Thomas used this imagery in the Adoro Te Devote. "Pie Pellicane..."
We now know it's scientifically unsound, simply not true -- but his heart was in the right place.

And then there's that pesky bit about the Immaculate Conception...

We know that St. Thomas philosophically built on Aristotle. But when you're talking about specific scientific facts, were Aristotle and the Greeks in general some kind of infallibles or pinnacles in matters of science? Did God make a promise to a bunch of pagan Greeks that they would never err in matters of natural science? I must have missed that chapter.

Thomas discusses at length the question of round vs. flat and comes up with the conclusion that if earth is stationary it must be flat. 

https://books.google.com/books?id=cR7qTyH_EfMC&pg=RA1-PA205&dq=Necesse+est+terram,+ad+hoc+quod+quiescat,+habere+figuram+latam&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwiSx-WUysLnAhW-knIEHQGPDZEQ6wEwA3oECAEQAQ#v=onepage&q=Necesse%20est%20terram%2C%20ad%20hoc%20quod%20quiescat%2C%20habere%20figuram%20latam&f=false

493. Secundam rationem ponit ibi: sed adhuc etc.; dicens quod adhuc addunt rationem ad idem, dicentes quod necesse est terram, ad hoc quod quiescat, habere figuram latam. Nam figura sphaerica facile mobilis est, quia in modico tangit superficiem: sed figura lata secundum se totam tangit superficiem, et ideo est apta ad quietem. Et ne credatur quod haec causa quietis terrae communiter ab omnibus assignetur, subiungit quod de motu et quiete terrae multi modi dicuntur, ut patebit ex his quae infra dicentur.

493. He gives a second argument at but they have another argument [352], and says that they add a further argument for the same, namely, that if the earth is to be at rest, it has to be flat. For a spherical shape is easy to move, because so little of it is in contact with a plane; but a wide shape is totally in contact with a plane, and is consequently apt for rest. And lest anyone believe that this explanation of the earth's rest is generally assigned by everyone, he adds that there are many different ways in which the motion and rest of the earth has been conceived, as will be plain from what will be said below.

Where?  In that "terra rotunda est" quote you and others seem to endlessly and uselessly cite in support of your bogus assertion?

You (and others) offered it up; I smashed it.  Get over it.

Sorry, but you seem to mistake me for someone else.