For Hall County, autumn is one of the greatest times of year.

Everyone is excited about fall fairs, weekend trips to the mountains and the nice change of chill in the air following a summer of sun.

One thing that excites me about fall is the change in leaf color, which transforms the look of the neighborhoods and woods in Hall County.

As the days become shorter, something in the trees and shrubs is triggered, allowing the entire process of color change to unfold.

Three different pigments are produced by the tree: chlorophyll, which is produced all summer and gives the tree its green color; carotenoid, which produces yellow, orange and brown colors; and anthocyanin, which produces red and purple colors.

The chlorophyll production reduces as fall approaches. As this happens, the green color of the leaves fades and allows the reds, oranges and yellows to appear. They were there all summer but hidden by the green.

If the weather is perfect at this time, the anthocyanin pigments or the reds and purples are produced due to the bright light and production of excess plant sugars in the leaf.

The amount of color and brilliance of the leaves in the fall is determined by temperature and moisture. A series of warm, sunny days and cool nights bring out the most color.

This year should be a good year for fall color because of the good supply of rain plants enjoyed all summer. All we need now are some cool nights and 65 to 75 degree days to continue.

Michael Wheeler is county extension coordinator for the UGA Cooperative Extension office in Hall County. You can contact him at 770-535-8293, www.hallcounty.org/extension. His column appears weekly and on gainesvilletimes.com/life.