There is a lot of scientific information about why leaves change colors. The average person though just wants to know the week the leaves will be at their most vibrant so an annual scenic trip can be planned. There is nothing more disappointing than missing their beauty because you are too early or too late. Even though calendars mark the official date when Fall begins, this date cannot be used to determine the exact time period the leaves will change colors. To help determine this, specific factors come into play. These factors also have a role in the length of time the colors will last.
The length of daylight hours, rapid temperature changes, and the amount of water the tree gets in the Spring and Fall, make up a big part of the equation. As Fall approaches, daylight hours dwindle and temperatures drop; these are two important factors that aid in identifying when the “changing of colors” will take place. For example, consider the leaves of a maple tree. When temperatures are a little above freezing, the leaves change to a vibrant red. But, if there is an early frost, the vibrance of the red color will decrease. Because of climate warming, leaves are continuing to manufacture food for a longer period of time; thus, they are keeping their green color longer than in past decades.
The amount of water the tree gets during its “feeding season” is also significant in determining when the leaves will change colors. When days are rainy and/or overcast, the intensity of the Fall colors will increase. If there happens to be a severe drought in the springtime, the growing season will end early and leaves will change color early. Some years, because of excessive dry conditions, the leaves will simply turn brown and fall off the branches. They bypass the color-changing phase altogether. When this happens, many people feel there was never a Fall that year; it simply skipped Fall altogether and went from summer to winter. People feel nature has cheated them! Nature really hasn’t though; the red to orange pigments are always in the leaves; they are just hidden by the overpowering green color.
Individuals and tour agencies would love to be able to predict a year ahead when the leaves will be at their peak colors. Now, they estimate and hope for the best. Every year people make plans to go on a site-seeing trip for a day, a week, and even longer to view the autumn leaves. In all corners of the continental United States and in between, people can view the foliage in their home state. In fact, a trip to any of the National Parks is a great way to see autumn at its best! Alaska has the honor of being the first of the 50 states to display autumn leaves. A great way to view them is by taking the train from Denali National Park to Anchorage. Hawaii only has two seasons, summer and winter. Autumn does not exist because Hawaii has little variance in temperature and the amount of precipitation.
Knowing all the information that needs to be collected to determine when the leaves will change color each year, most people (like myself) will just look it up on the internet.
Somewhere in the United States, it’s time to view the colors!
https://www.esf.edu/pubprog/brochure/leaves/leaves.htm
https://www.tripsavvy.com/a-state-by-state-guide-to-fall-colors-3362305
https://www.hawaii-aloha.com/blog/2015/12/17/what-and-when-are-hawaiis-seasons/
