Clouds are made up of millions of tiny water droplets or ice crystals suspended in the air, and are named according to their shape and height.
Stratus clouds are thin layers formed from 500 metres of the Earth's surface and above, by slowly rising and cooling air.
When air rises more quickly it produces puffy, cumulus clouds. Cumulonimbus are great towering thunder clouds.
A third type of cloud is cirrus, wisps of cloud high in the sky.

The bible refers to clouds when showing forth the presence of God in the old testament and when announcing His return to this earth in the new testament.

In the old testament He led forth His people, Israel out of the captivity of Egypt and into the promised land.
And His presence never left them.

And the LORD went before them by day in a pillar of a cloud, to lead them the way; and by night in a pillar of fire, to give them light; to go by day and night: He took not away the pillar of the cloud by day, nor the pillar of fire by night, from before the people.
Exodus Ch 13 vv21,22

In the new testament the Lord's return to this earth is declared. And it comes with a warning to those are not ready for His return.

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.
Revelation Ch 1 v 7