When it gets cool, the dark green (Chlorophyll-A) goes away, & light green shows. When it gets cold, the light green (Chlorophyll-B) goes away, and yellow shows. When it get colder yet, the yellow (Xanthophyll) goes away and the red shows. When it gets coldest, the red (Carotene & Anthocyanin) goes away & the leaf turns grey. When the wind blows, so goes the leaf…. Not all leaves have all these pigments, & the timing depends on the leaf structure & the amount of sugar (anti-freeze) in its leaves….
Sorry, it has to do with the length of sunlight (including what shines through clouds). Otherwise, leaves in warm winter regions would never turn at all. It varies with latitude. That is why Canadian Thanksgiving (a harvest festival) is October 12 this year, and leaf-viewing has already started in northern states, while here, the only non-green leaves are due to drought, not temperature.
Lamberger almost 8 years ago
When it gets cool, the dark green (Chlorophyll-A) goes away, & light green shows. When it gets cold, the light green (Chlorophyll-B) goes away, and yellow shows. When it get colder yet, the yellow (Xanthophyll) goes away and the red shows. When it gets coldest, the red (Carotene & Anthocyanin) goes away & the leaf turns grey. When the wind blows, so goes the leaf…. Not all leaves have all these pigments, & the timing depends on the leaf structure & the amount of sugar (anti-freeze) in its leaves….
hippogriff almost 8 years ago
Lamberger
Sorry, it has to do with the length of sunlight (including what shines through clouds). Otherwise, leaves in warm winter regions would never turn at all. It varies with latitude. That is why Canadian Thanksgiving (a harvest festival) is October 12 this year, and leaf-viewing has already started in northern states, while here, the only non-green leaves are due to drought, not temperature.