In early Autumn, it seems like Nature's colors look different than they do at mid-summer. What is going on

Question

with the light so that there seems to be a slight color shift in Autumn?

Answer 1

You are very observant. There is a shift due to the distance the light travels through the atmosphere changing over the seasons called the angle of incidence. In midsummer when we are closest to facing the sun the light has the shortest path, autumn sees the mid length path, and winter the longest.

Light is scattered causing diffusion. The scattering is caused by particles of dust & water in the atmosphere. Even the air molecules scatter light some in the short wavelengths making the sky blue by this process. The longer the path through the air at the vernal equinox causes a color shift in the light reaching the ground. As more blue is scattered the light becomes 'warmer' or yellower, shadows soften as they lengthen.

The same happens over the course of the day. Midday sun is white, sunset is red, orange and yellow. During sunset/sunrise the blue colors get scattered out of the direct light path from the sun to you.
Photo of evening in fall showing color shift
http://www.fotocommunity.com/pc/pc/display/10762767

Plants absorb the blue wavelengths more than red except for chlorophyll alpha that peaks highest in the red. Chlorophyll beta has its primary peak in the blue at 470nm.
Xanthophyll absorbs well at 400-530 nm (blue) and
beta-carotene absorbs most strongly between 400-500 nm (blue). What a pigment doesn't absorb it reflects. Chlorophyll a reflects green but dies out in the cold so the leaves shift to the remaining active pigments. They reflect the yellow and red longer wave lengths. This combination of increased incidental light scatter and leaf reflection of long wave length make the entire autumnal color scheme warmer and softer.

Answer 2

I just read an article about this last week.

Green leaves have red pigments in them that are hidden by the chlorophyll in them when the leaves are still alive. When a deciduous tree (one that drops leaves every year) goes into autumn, the energy in the leaves and stems goes back to the root system for storage over the winter.

As the chlorophyll starts to seep back into the tree, the red pigments combine with the green chlorophyll to give the leaves a yellow appearance. When the chlorophyll is gone, the leaves appear red. This red pigment actually functions as a sunscreen, so the leaves won't get damaged by the sun before the energy transfer back to the root system is complete.

Answer 3

It's not the light! It's due to the photosynthesis in the leaves stopping. In the Autumn the leaves die and fall from the tree. As they die, they change colour.

Answer 4

The technical term is senessence, that is while the chlorophyll tiers drop with the aid of fact the image voltaic tiers drop in autumn i think of, and the leaf loses the golf green color. additionally the abscission layer between the top of the leaf stalk and the main considerable branch seperate and then the leaf falls.