How does light work ..canopy penetration

This is how light works on a simple example for anybody learning about what kinda lights to buy and what info is important.
I am NOT an indoor grower I cant help you decide. But i can give you mother natures example and you can re create it.
First foremost.
The red spectrum encourages root growth and the blue spectrum keeps plants short and bushy. Ie: sky blue no reaching/not leggy
That's why most led lights are red n blue. The amount of one color over the other let's you decide what growth in more valuable to you by adjusting color red blue ratio. ( look at like a "receipe" more of this color and less of that color will make it do this)= desired outcome
Ultraviolet the end of the spectrum technically hurts your plant but in low doses it can be used to build up the plants immune system. ( that's not for the beginner tho)
Allso "far reddening" is the practice of introducing a 15 minute flash of red light only before and after your lights come on and off everyday. Said to mimic the far red color of sunset and rise which in turn wake up and put it too sleep that how plants guage there age.
Its akin to some one turning ur bedroom light on full blast at 4 am and blinding you. The " light receipe is supposed to gain 2 hours of grow time per day extra... this I have not tried.
Nanometer of the light spectrum chart I believe its 460 nanometer mark is the light intensity that captures the most usable red and blue etc light at one particular spot in the chart. That's the closest color as the chart is layed out like a rainbow to sky blue.. which is just what they are trying to mimic The Sky.

When you look up from below any plant toward the sky ( see photo attached) the top leaves appear bright green the lower you get, as more leaves overlap one another , the darker they get, until its almost dark forest green on the lowest level.
That is because..
The color red and blue are being absorbed by each leaf its literally a light filter for red and blue. The top leaves take all the red and blue they need. Then some extra makes it to the next lower set ( now darker) then down and down till there is no red and blue left for the lower leaves. They receive only the color (green) the reason every plant is green is cause they absorb all the red and blue and all we can see with our eyes is the color left behind (green).
Enter a grow room with red and blue LEDs its looks purple shine a green light in the room and it look like normal daylight again. That's the reverse. Now .. a ( greenheadlamp on at night when it's dark in your grow room gives you ability to work on stuff ( defoilate , spray for pest etc.) During hours when you cant have a light on in the room as the plants cant technically see green. I mean they can but it won't hurt them in small doses. And it's probably not a strong enuff bulb on a headlamp to influence the following effects.
This happens for a reason.
As the lowest leaves receive only green light waves it triggers the plant to kill off those leaves because they are no longer gathering light and making glucose ( sugar or photosynthates). No more sunshine
That is how nature creates a canopy.
Make sure your lights have the ability to penetrate your canopy!
This is why defoliation may be a good choice in flowering. Getting light to the bud sites.

Anyway I hope this explained light
The rabbit hole gets more technical and there is a lot more to it but this a good general idea of how and why

 

Clever trick .. that's a great visual aid!