Exegesis:

V. 27 is almost completely identical with Mk. 13.26. The differences between Mark and Luke are that the former has en nephelais in the plural and the letter en nephelē in the singular, without appreciable difference of meaning; and that Mark reads meta dunameōs pollēs kai doxēs ‘with great power and glory,’ and Luke, meta dunameōs kai doxēs pollēs ‘with power and great glory.’ In both cases pollēs goes with both substantives.

Translation:

See the Son of man coming, or, ‘see how the Son of man comes,’ ‘see the Son of man, who will be coming.’

In a cloud, i.e. enveloped in a cloud, in the midst of a cloud.

Glory, see references on 2.9.

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.