The Bible speaks of several differences between conditions on earth before, and after, the flood. The fossil record also reveals various changes. Several of these biblical truths and observable facts have been combined into an explanation known as the "Canopy Theory." While we may not speak of this theory as biblical fact, yet many consider this possible explanation of the pre-flood world to be worthwhile.
The "Canopy Theory" states that a large water-vapor canopy encircled the pre-flood earth above its atmosphere, producing a universally warm, mild climate by filtering and trapping the sun's rays in a "greenhouse-type" fashion. At God's command, the canopy collapsed, causing millions of tons of water to fall to the earth, which produced both a universal flood and new atmospheric conditions on the earth.
Canopy - An overhanging, protecting covering
Pre-flood - Before the worldwide flood at the time of Noah
Encircled - Surrounded; enclosed; formed a circle around
Atmosphere - The body of air surrounding the earth
Universally - Wholly; entirely; worldwide
Collapsed - Caved in; having given way