Objection 1. It would seem that an angel is not in a place. For Boethius says (De Hebdom.): "The common opinion of the learned is that things incorporeal are not in a place." And again, Aristotle observes (Phys. iv, text 48,57) that "it is not everything existing which is in a place, but only a movable body." But an angel is not a body, as was shown above (Article 50). Therefore an angel is not in a place.
Objection 2. Further, place is a "quantity having position." But everything which is in a place has some position. Now to have a position cannot benefit an angel, since his substance is devoid of quantity, the proper difference of which is to have a position. Therefore an angel is not in a place.
Objection 3. Further, to be in a place is to be measured and to be contained by such place, as is evident from the Philosopher (Phys. iv, text 14,119). But an angel can neither be measured nor contained by a place, because the container is more formal than the contained; as air with regard to water (Phys. iv, text 35,49). Therefore an angel is not in a place.
On the contrary, It is said in the Collect [Prayer at Compline, Dominican Breviary]: "Let Thy holy angels who dwell herein, keep us in peace."
I answer that, It is befitting an angel to be in a place; yet an angel and a body are said to be in a place in quite a different sense. A body is said to be in a place in such a way that it is applied to such place according to the contact of dimensive quantity; but there is no such quantity in the angels, for theirs is a virtual one. Consequently an angel is said to be in a corporeal place by application of the angelic power in any manner whatever to any place.
Accordingly there is no need for saying that an angel can be deemed commensurate with a place, or that he occupies a space in the continuous; for this is proper to a located body which is endowed with dimensive quantity. In similar fashion it is not necessary on this account for the angel to be contained by a place; because an incorporeal substance virtually contains the thing with which it comes into contact, and is not contained by it: for the soul is in the body as containing it, not as contained by it. In the same way an angel is said to be in a place which is corporeal, not as the thing contained, but as somehow containing it.
And hereby we have the answers to the objections.
Source: Summa Theologica (New Advent)