Wild Wonderful Weather: Breaking down the science behind fall colors, tell me about this news in (https://www.wowktv.com/weather/wild-wonderful-weather/wild-wonderful-weather-breaking-down-the-science-behind-fall-colors/)
09-09-2026
The article from WOWK 13 News (part of their “Wild Wonderful Weather” educational series) explains the meteorological and biological processes that cause leaves to change color in the autumn:
- The Role of Daylight and Chlorophyll Breakdown: During spring and summer, leaves are green due to chlorophyll, the pigment plants use to convert sunlight into food through photosynthesis. As autumn approaches, days become shorter and the amount of sunlight decreases. This change signals deciduous trees to stop producing chlorophyll. As the green pigment fades, other underlying pigments are revealed.
- Carotenoids and Flavonoids (Yellows, Oranges, and Browns): Pigments like carotenoids (responsible for orange hues) and flavonoids/xanthophylls (yellow hues) are present in the leaf tissue all year long. They remain hidden beneath the intense green of chlorophyll until production halts, allowing hickory, birch, and tulip poplar leaves to reveal vibrant yellows and golds.
- Anthocyanins (Reds and Purples): Unlike yellow and orange pigments, red and purple pigments (anthocyanins) are produced primarily in early autumn. When veins in the leaf begin to close off (forming an abscission layer at the stem), sugars become trapped. With plenty of light and trapped sugars, chemical reactions produce anthocyanin pigments, giving sugar maples, sumacs, and dogwoods their rich red and purple shades.
- Weather Conditions That Create Peak Foliage: The intensity and timing of fall foliage depend heavily on late summer and autumn weather:
- Ideal conditions: A succession of warm, sunny autumn days combined with cool, crisp nights (above freezing). The sunny days promote sugar production, while the chilly nights prevent sugars from flowing out of the veins, leading to brilliant red coloration.
- Detrimental conditions: Severe droughts cause leaves to turn brown and drop early. Prolonged cloudy, warm periods mute colors, while an early hard freeze kills the leaves prematurely before peak color can develop.