Genesis 1:6-10
6 Then God said, "Let there be an expanse in the midst of the waters, and let it separate the waters from the waters." 
7 God made the expanse, and separated the waters which were below the expanse from the waters which were above the expanse; and it was so. 
8 God called the expanse heaven. And there was evening and there was morning, a second day. 
9 Then God said, "Let the waters below the heavens be gathered into one place, and let the dry land appear"; and it was so. 
10 God called the dry land earth, and the gathering of the waters He called seas; and God saw that it was good. 

The Canopy Theory is not in the bible, but it is a guess by man about how God might have created the earth pre-flood.  The Canopy Theory suggests that a layer of moisture (maybe a cloud, maybe a mist, maybe a layer of water) surrounded the earth.  We do not know the density or the thickness of this layer so, as you can see, this is just a theory.  This canopy would have created a different type of surface pressure on the earth, a different oxygen content on the earth, and an earth that did not have direct UV rays from the sun hitting the surface of the planet.  This is based upon verse nine above.

The surface pressure is important because it is the gravitational pull that wears our knees, ankles and hips out today.  Larger animals would have found it easier to walk around with a different surface pressure.  The oxygen content is important.  When a person goes in the hospital, it is common for the medical staff to attach oxygen to a patient.  The UV rays of the sun wear everything on the planet surface out.  That is why you must repaint your house and your car.  Those rays can be harmful to the skin if a person is over exposed and cause sunburn. 

Genesis 7:4-5
4 For after seven more days, I will send rain on the earth forty days and forty nights; and I will blot out from the face of the land every living thing that I have made." 
5 Noah did according to all that the Lord had commanded him. 

Genesis chapter seven deals with the flood.  God sent the rain.  God closed the door of the ark.  People have made calculations regarding the amount of water needed to cover the highest mountains and we do not have enough moisture in our present day atmosphere to do the job.  As a matter of fact, they do not think that all the moisture around our planet could get more than a foot or two over the surface of the earth, but of course, that all depends upon where you live.  New Orleans which is below sea level would be under water while Denver might not be.  So, where did the water come from?  The bible also mentions water from below.  How much water came from below the surface of the earth and was those underwater sources of water what created great canyons like the Grand Canyon?  These are all theories. 

Genesis 7:16-20
16 Those that entered, male and female of all flesh, entered as God had commanded him; and the Lord closed it behind him. 
17 Then the flood came upon the earth for forty days, and the water increased and lifted up the ark, so that it rose above the earth. 
18 The water prevailed and increased greatly upon the earth, and the ark floated on the surface of the water. 
19 The water prevailed more and more upon the earth, so that all the high mountains everywhere under the heavens were covered. 
20 The water prevailed fifteen cubits higher, and the mountains were covered. 

God's Word is God's Word and a theory is just man's ideas.  Facts are facts.  Science is suppose to be based upon fact.  A theory is man's best guess about an unknown 'issue/idea/origin' based upon facts. 

Some scientists, who do not believe in God, tend to present their personal theories as fact regardless of what the actual real facts really represent.  I do not appreciate, or respect, a scientist who does not stick to the hard, cold actual facts when presenting their ideas.  When you get into areas of origin and where everything comes from, you are actually talking about religion. 

I say religion because when a scientist tries to describe the origin of mankind and origin of our world, well that is exactly what God claims He did when He made the heavens and the earth.  So if you are getting into that realm and denying the existance of the Living God, you are establishing a religion.  Please just be man enough to say what you are doing and do not hide behind a lab coat and call yourself a 'scientist' like you have all the answers in life.  You are just a man.  A few years ago you were wearing a diaper and breast feeding from your mom. 

The oldest written documents we have today are just a few thousand years old.  When a scientist starts talking about events that happened back millions and trillions of years ago, he has nothing to base his 'theory' on except his personal opinion.  This 'scientist' is just a man presenting his theory and it is not a fact, but his human opinion.  I would be more tolerant if this 'scientist' would talk about events that were tens of thousands of years ago, but to go back millions and trillions of years in the past and talk about events as if they happened yesterday is complete and total non-sense. 

As I personally try to understand the origins of life as a Christian, I go to the only information provided by God regarding the subject and try to put the pieces of fact around us together as best as I can and try to make some sort of logical sense out of all the data.  The canopy theory is just man's best guess based upon a few passages from God's Word.  These are not facts, but just a collection of observations regarding how God possibly made this world.

One area that must be addressed is the length of life described in the pre-flood days of the Old Testament.  How could any man live so long?  What changed on our earth to shorten the average life span of man? 

Some people will speculate and say the creation story in Genesis was made up.  Really?  If the flood story was made up by a man, why would he list the life spans going way beyond any normal life spans of today.  If a man was writing a story that he wanted people to believe, he would not include stuff like extended life spans which are unbelievable.  God tells man to believe and have faith in Him.  I do.  Think about the covenant of circumcision given to Abraham.  God says that this is His Covenant in regards to the rescue plan God has for this world.  No man in is right mind would ever create a religious system where they cut off anything associated with his private parts.  God is not a respector of man and God told Abraham that from your seed the world will be blessed.  So, here is My Covenant.  I am sure that when Abraham was told about circumcision that he was taken a back, but he did obey. 

When we look at the present age and consider the recent findings of the fossils of dinosaurs, we must ask ourselves how did these dominate creatures die out?  What could have killed these creatures?  Here is a bigger question, how do we make fossils?  People and animals simply buried in the dirt will decay into dust.  We know that to be fact.  Fossils are only created when a creature is covered 'all at once' by a solution like concrete or like lava such as happened in Pompeii when the people were covered 'all at once' after the volcano exploded.  The bones dissolved into dust as they do, and an empty void is left from the bones in the rock/sediment/lava before the bones dissolved into dust. That is what makes a fossil.  The bones you see in the museum are just the void areas filled with a liquid solution that has hardened to create what looks like the bones as the existed prior to that creature being covered 'all at once' by a liquid solution like sediment or lava. 

So, what event could have happened on a world wide scale that could create some form of thick liquid to bury all these massive creatures?  The bible says the world was flooded.  Every ancient people from all over the world have a version of a flood story.  The bible says God called the animals into the ark.  It seems to me that God did not call these dinosaur creatures into the ark and that it was His decision that they die in the flood.  This is His world and I guess God knows best in regards to His creation.

Do you know about the Pterosaur?  This is sometimes referred to as the big flying dinosaur.  How did that large flying bird actually create lift in our atmosphere?  It is impossible.  Fact: His size/weight to wing surface ratio is just too large for that creature to create lift in our present atmosphere.  Based upon that fact, we must conclude that the atomoshere must have been different whe he did fly. 

It is so funny when reading and doing research on any pre-flood creature because these 'scientists' talk about how this creature just evolved the power to fly hundreds of millions years ago.  Remember, the oldest written word we have in existence today is only a few thousand years old.  I'm sorry, but that 'religion' presented by these 'scientists' takes so much more faith to believe in than anything presented in the bible.  At least Jesus, David, Moses and Abraham are real historic figures.  We actually have copies of writings from Moses and David.  What proof do we have that this creature evolved the power to fly.  Maybe, just maybe the Living God made the Pterosaur just as he existed.  It that really so hard to believe?  To say this creature just decided one day that he wanted to fly so he simply grew himself some wings is such a ridiculous statement from educated people that it is absolutely crazy.  Actually, it is sad.  If that is the way life actually operates, then I want the ability to dunk a basketball.  So, I guess all I need to do is just grow myself some leaping legs.  Maybe I need to wait a few million years? 

Fact: Amber from prehistoric days captured an air bubble and the oxygen content inside that bubble was at 35%-40%.  Our atmosphere contains an oxygen content around 20%.  How did that bubble get 35%-40% oxygen?  Was pre-flood oxygen different from present day oxygen?  If so, why?  Could that explain part of the long life span question from Genesis prior to the flood?  According to a study from a U.S. Geological Survey, they state that they think the drop in oxygen from 35% to our present day 20% occured about the same time that dinosaurs disappeared.  As a Christian, I say the dinosaur died out in the flood.  They say it just happened, and of course, it happened 65 million years ago. 

Fact: Water molecules have been discovered in the middle atmosphere where rain clouds do not go.  How did those get there?

First, we must describe the various layers above earth.  From the surface of the earth up about 10 miles from the equator and about 5 miles above the poles is the area called the troposphere.  The troposphere is where we have our weather from storms to winds to rain plus it has all our oxygen. 

The second layer above the earth is the stratosphere.  The stratosphere starts where the troposphere starts and ends about 30 miles above earth.  The stratosphere is the layer where commercial airliners cruise to optimize fuel burn and stay above any rough weather that might occur down in the troposphere zone. 

The third layer above the earth is the Mesosphere which is about 30 miles above earth and varies in depth from 20miles to 30 miles thick.  The forth layer above the earth is the thermosphere which is the zone where the International Space Station maintains its orbit about 200 miles from earth. The stratosphere, mesosphere and the lower section of the thermoshoere are collectly called the "middle atmosphere".  The fifth layer above earth is the magnetosphere. 

The real tough part of describing a canopy in theory is that we do not know the thickness, reflectivity, content, height above the earth or what effects it would have on the earth such as temperatures, oxygen content and gravitational pressure.

I have read scientific rebuttals against the canopy theory that include; 1) the weight of moisture in the air is more than could be possible, 2) the temperature under a canopy would increase beyond what is tolerable, and other opinions or theories.  But these are not based upon facts from scientific observation.  They are based upon man's best guess about how it might have been like under a canopy.  The actual situation under a canopy has just too many unknown variables to really establish a scientific evaluation based upon fact.