Revelation 1:7

7 Behold, he cometh with clouds; and every eye shall see him, and they also which pierced him: and all kindreds of the earth shall wail because of him. Even so, Amen.

When Jesus comes, He will come with the clouds of heaven. From the earth, they will look like clouds but perhaps they are what angels use for transport. When Jesus left, He was taken up into a cloud. A cloud by day that looked like a pillar of fire at night led Israel in the wilderness for forty years. The scripture says this cloud was an angel. There are scriptures that say the Lord descended in a cloud and rideth upon a swift cloud. Most say the clouds are the saints who come with Him riding on white horses (Revelation 19:14). Whatever the makeup of these clouds, when Jesus comes with these clouds the Lords appearance will be glorious.

When Jesus comes with clouds, everyone on earth will see Him including those that pierced Him. Those that pierced Him are dead, so it is certain that even the dead in Hades will see the second coming.  The incorrect doctrine of soul sleep is disputed by this verse. God will have no problem converting the visual of the second coming to the eye of the soul so that all will see Him. Actually, this verse is fulfilling what Jesus said:

Matthew 26:64 Jesus saith unto him, Thou hast said: nevertheless  I say unto you, Hereafter shall ye see the Son of man sitting on the right hand of power, and coming in the clouds of heaven.

This verse also indicates that Jesus will have physical form at His coming. He will not come as a mystical spirit to indwell the people or a person. The Holy Spirit indwells people but Jesus will come back physically and every eye will see Him.

At His coming, all tribes of the earth will be in fear and trembling.

Revelation 6:16 And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb: 17 For the great day of his wrath is come; and who shall be able to stand?