ἁρπαγησόμεθα ἐν νεφέλαις εἰς ἀπάντησιν τοῦ Κυρίου εἰς ἀέρα
Clouds are heavenly like the air. The celestial meeting discussed in 1 Thess 4:17 surely does not suggest that the meeting occurs on earth.
E. J. Richard (First and Second Thessalonians. Collegeville, Minn: Liturgical Press, 1995) suggests four bits of data that point toward a heavenly entrance in 1 Thess 4:17. I want to list three of the factors that Richard discusses.
(1) The clouds and "snatching" imagery indicate that
the chosen ones enjoy an "aerial meeting." The Greek term
for air is employed within Jewish cosmology to delineate
the "ethereal region between heaven and earth." See
Richard 247 and TDNT 1:165-66.
(2) The Son of Man sends out angels to gather his elect when he comes in the clouds (Matt 24:30-31).
(3) 2 Cor 5:8 indicates that the believer's future dwelling will be heavenly sans an earthly or fleshly body. Some would argue that human bodies will be glorified by the Lord. See Philippians 3:20-21.