Science Behind... Leaves Changing Color

Talk nerdy to me...why do leaves change color? 

Dust off that Biology book to answer why leaves change color. It is the peak right now in Northeastern Ohio and the colors are just amazing.  This year with the cooler temperatures have been a great set up for a wonderful palate of fall foliage! There are a ton of foliage maps to check out. I like to look at this site that has current pictures and maps to see where is peak or just turning.

do you remember those days?

First you need to know why plants are green. I'm sure we all remember from our jello model of the plant cell back in elementary school that chloroplasts make chlorophyll and this gives leaves a green color. But why? It has do with light... the little particles called photons. The wavelengths of these photons that don't absorb we see as color. Chlorophyll absorbs violets and red wavelengths and does not absorb green hence the green leaf color. 

Ok but why do leaves change color? As you get further away from the equator the angle of the sun changes giving us the seasons. As we transition into fall there is less direct sunlight which which means less chlorophyll (and less photosynthesis reactions) is produced and the green color fades.

 Now living things are amazing and have some back up plan. There are other pigments in the leaf called carotenoids and anthocyanins that absorb a different spectrum of wavelengths. They show up as the yellows, reds, and oranges we see in the fall. These pigments are always there but get covered up until chlorophyll fades. Why the leaves fall off after this change is a whole different discussion..if you really want to know message me.

look at all the different pigment colors!

Different trees have different varieties of pigments giving us all the beautiful fall colors. Carotenoids are not light dependent and will produce yellow color, while anthocyanins need light (and with a little chemistry) give us the nice red color. Temperature affects the rate of chemical reactions so it is also a factor in leaf color. But the number one key to fall foliage is light: sunny days provide bright colors, while lots of overcast days will lead to yellows and browns.

There it is in a super simplified nutshell is why leaves change colors....while the science behind it is super cool it's best just to get out and enjoy the show nature painted this year!

Happy Adventuring!