Think of autumn and you probably conjure up images of walks along tree lined lanes, the golden leaves crunching under your feet.

Well, reality is usually very different and more often than not those golden leaves get blown off the trees on one wet and windy day, not to be seen for another twelve months.

This autumn though the picture is rather different. Dry, sunny days and cold frosty nights are predicted to bring out the best of the autumn colours across Wiltshire.

Why do leaves change colour?

The leaves change colour in response to changing light levels.

During spring and summer the leaves produce green chlorophyll which is used to synthesise water and carbon dioxide into sugars, which are stored until needed.

As the length of daylight reduces during the autumn the supply of water to the leaves is cut off, trapping the glucose and waste products.

Without a supply of water chlorophyll production begins to drop off. As the green of the chlorophyll disappears other colours which have previously been obscured by the green, come to the fore.

The leaves change colour in response to changing light levels.

The orange and yellow colours come from carotene and xanthophyll. The red and purple colours come form anthocyanin pigments.

The intensity of the colour depends on the concentration of the stored sugars.

The sunny early autumn days have produced large amounts of sugars within the leaves whilst the dry weather has allowed these sugars to become highly concentrated.

So a walk in the countryside over the next week or two will perhaps provide some good photo-opportunities as nature puts on a show of colour.

You can track and add to the spread of seasonal changes by logging on to phenology.org.uk.

And click here to find out more about phenology and the response of flora and fauna to weather and climate.