Can anyone tell me why red light triggers/aids a flowering response in plants? And similarly, I guess, why blue light encourages growth? Not necessarily the mechanisms involved in the process, but how this function correlates to nature? My first inclination was to point at the seasons as the cause (longer wavelengths maybe during fall months), but the wavelengths of light made available by the sun are no different during the summer and fall; the amount of light is what changes. I feel like the answer is something super obvious and I'm just missing it completely
the earths atmosphere distorts the suns rays into longer or shorter wavelengths like you said making it red or blue. This has to do with the sun's relative position to earth which changes during the seasons.
That explanation, while close, isn't really correct. The Earth doesn't move "away" or "towards" the Sun, and it's the tilt/orbit of the Earth that causes the seasons. This is more accurate: Let me expand upon this; Since the Earth's North/South axis is tilted about 23.5 degrees, as the Earth moves around the Sun, the North and South hemispheres get slightly closer and further away at different times (seasons) throughout the year (it takes ~365.25 days to orbit the Sun). Let us assume we are talking about the Norther Hemisphere of the Earth. As you can see in the following image, during Summer the Northern Hemisphere is leaning towards the Sun, while during Winter the Norther Hemisphere is leaning away from the Sun. In addition to slightly affecting the distance relationship of the Northern Hemisphere to the Sun (and subsequently temperatures and light-radiation intensity), the tilt affects the angle of incidence the Sun's light has upon the Northern Hemisphere. This angle increases during the Winter months (more obtuse angle) and decreases during the Summer months (more acute angle). This is important, remember it. Now, when light passes through a prism or medium of some sort (our atmosphere for example) the different wavelengths of light are split and refracted at different angles (see below). As can be seen, blue refracts the greatest amount, while red refracts the least. When this is combined with the greater angle of incidence the Sun has during the Winter months, more blue light is refracted at an angle such that it never passes through our atmosphere, it is simply rebounded off into space. This doesn't happen as much to the red light radiation because it refracts less. Meaning that there is a higher concentration of red light radiation during the Winter months, as opposed to the Summer months when more blue light makes it through due to the more perpendicular angle of incidence the Sun's light has. Feel free to hit me up with any further questions! -Dreamer