The Correlation. Correlation is a measue of how close the line fits the points that you found in your experiment. Anyone can say whether they think the line is a good fit or not, but to measure it exactly, we use the correlation coefficient: R2.
As the seasons change and the amount of sunlight decreases, less chlorophyll is produced, and the leaves appear less green. Chlorophyll is broken down into simpler compounds at a constant rate, so green leaf color will gradually fade as chlorophyll production slows or stops.
How Leaves Turn Yellow. Yellow colors that were always present in leaves become unmasked as the chlorophyll is broken down and absorbed. Called carotenoids, these are the yellow pigments that give trees like birch, beech and tulip their bright fall colors.