Fall Foliage Part I: What Causes the Leaves to Change Color?

Saturday is the first day of Autumn. This is the first of a three-part series on Fall Foliage in New England. Today, I take a look at why the leaves change colors and what ingredients are necessary for optimum viewing of Autumn’s splendor. The next installment looks at the when the colors reach their peak in southwestern Connecticut and New England. Finally, I’ll explore the best places to view the wide array of colors locally and across Connecticut.

Autumn officially arrives Saturday morning at 10:49 EDT, and it will begin to feel like it later this weekend after a cold front pushes through the region Saturday night. Temperatures have already fallen into the 40s across interior southwestern Connecticut earlier this week, and Monday's forecast high temperature won't escape the 60s. Naturally, it’s time to look ahead to what this year’s Fall foliage may bring. Have you noticed any leaves beginning to change color yet? I have. And have you wondered if our weather has cooperated to give us optimum colors this Fall? You’re certainly not alone.

I’ve only noticed just a few trees beginning to show their Autumn colors so far. I’m sure you’ve wondered why the leaves change color. All leaves contain a green pigment called chlorophyll, which is instrumental in photosysnthesis. That’s the process in which energy from sunlight is used to make the sugars that feed the tree or plant. During the growing season, it is continually replaced, but eventually it breaks down.



As the days continue to get shorter and cooler, the environment is less conducive to growth. Sunset is before 7:00 p.m. now. Photosynthesis, naturally, is suppressed. Chlorophyll continues to deteriorate, and not much is replaced. The rate of breadown increases dramatically after the first frost. The yellow and orange pigments, known as cartenoids, which have been in the leaves all along, become radiant as the chlorophyll levels continue to decline.

Red and purple pigments, called anthocyanins, develop in late Summer and Fall, largely in response to the first frost. These can be seen in some tree species such as red and sugar maples. Leaves with a variety of chlorophyll levels create the colorful landscape that we’ve come to appreciate in the Northeast in the Fall. The shades of color are also influenced by how the pigments interact with other factors in the leaf, including the pH level and what minerals may be present.



What are the weather factors which ultimately hasten the beauty of the fall colors? The most important factors are sunny, warm days and cool nights. Thus far this month, the average temperature 1.5 degrees above normal. The first nine days this month were warmer-than-normal, but the weather pattern has begun to change. Eight of the last 11 days have been cooler-than-normal. The normal high and low temperatures for southwestern Connecticut today are 72 and 56 degrees, respectively.

Another ingredient necessary for the brilliant colors is rain, and we haven’t had much of that this month. In fact, there have been only five days with measured rain this month, and there has been just one day with measured rain since September 8. Thus far, we’ve received just under two inches (1.91″) of rain for September, which is below the 2.29″ normal through today. August featured below-normal precipitation, too, with 3.33" of rain, well below the 3.96" normal for the month. Cumulatively, for the year, we’ve measured 27.12″ of rain, well below the 31.19″ norm.



Too little rain can cause trees to “shut down” early and cause stress for trees. A quick peek at the week ahead shows that some much-needed rain will arrive Sunday. Next Monday, I’ll take a look at the best locations for viewing the Fall foliage in southwestern Connecticut and Southern New England.

Paul

Autumn Officially Arrives This Saturday Morning

Now that the gusty winds and heavy rain of yesterday have moved away, we'll enjoy a pleasant stretch of weather over the next few days. Officially, nearly an inch (0.88") of rain fell at Sikorsky Memorial Airport in Stratford yesterday, and a wind gust of 47 miles an hour was recorded. Any clouds will give way to developing sunshine today, but it will be breezy and less humid with a high temperature near 70 degrees.

The Autumnal Equinox officially arrives this Saturday, September 22, at 10:49 a.m. Eastern Daylight Time. That's when the direct rays of the Sun are above the Equator, technically marking "equal day and equal night" across the face of the globe. As the direct rays of the Sun continue to move South of the Equator, the Southern Hemisphere will be enjoying the start of Spring next week.

However, here in the Northern Hemisphere, the amount of daylight continues to dwindle, and the Sun now sets well before 7 o'clock in the evening. Recall that in late June, during the time of the Summer Solstice, the Sun set at 8:30. We've lost more than an hour-and-a-half of daylight just in the evening alone over the last three months.



So why does the Equinox happen? The seasons of the year are caused by the 23.5º tilt of the Earth's axis. Because the Earth is rotating like a top, it points in a fixed direction continuously toward a point in space near the North Star. That's why the North Star appears to be the only star which doesn't move in our night sky. However, the Earth is also revolving around the Sun. During half of the year, the Southern Hemisphere is more exposed to the Sun than the Northern Hemisphere. During the rest of the year, the reverse is true.



At noontime in the Northern Hemisphere the Sun appears high in the sky during the Summer and low in the sky during Winter. It is highest at the Summer Solstice in late June and lowest at the Winter Solstice by the end of December. The half-way points in the year are called the Equinoxes. It is the time of the year when the Sun rises exactly in the East, travels through the sky for 12 hours, and sets exactly in the West. The photo below shows visitors at Stonehenge on the Salisbury Plain in England.



However, on the Autumnal Equinox in southwestern Connecticut, the Sun rises at 6:40 a.m. and sets at 6:50 p.m., giving us 12 hours and ten minutes of daylight. That has to do with the angle at which the Sun rises and sets. Actually, "equal day and equal night" occurs for us on September 25th and 26th when we receive just about 12 hours of daylight and 12 hours of darkness.

Take advantage of the pleasant weather over the last few days of Summer. After a clear and cold night tonight, tomorrow and Friday will be mostly sunny and seasonable with highs in the upper 60s to lower 70s. Fall arrives on a milder note under a mix of clouds and sunshine with a high of 75 to 80 degrees. There will be a few showers later Saturday night into Sunday, but the weekend will be fairly quiet as we usher in a new season.

Paul

Nationwide Hot Streak Extends Over First Eight Months of the Year

By now, I'm sure you're well aware of our current streak of 18 straight warmer-than-normal months across southwestern Connecticut. The last month to feature cooler-than-normal weather was February of 2011. In case you're wondering, this month's average temperature of 70.3 degrees is 1.9 degrees above normal. There is a distinct possibility our warm streak may be extended to 19 months. However, the warm weather pattern isn't just confined to the Northeast.

The first eight months of 2012 were the hottest ever recorded in the continental United States, and the Summer period of June, July and August was the third hottest ever, the National Climatic Data Center reported Monday. Although the August average of 74.4 degrees Fahrenheit made it only the 16th hottest August on record, the fact that July 2012 was the hottest July ever and above average temperatures earlier in the year kept 2012 atop the record books.

The nation as a whole is averaging four degrees Fahrenheit above average for the year. That's a full degree higher than the same period in 2006, the second hottest January-August on record. Record keeping began in 1895. Locally, each of the first eight months of this year has been much warmer than normal, with the temperature departure much more pronounced during the first three months of 2012. The average temperatures for January, February, and March, were 5.6, 6.3, and 7.8 degrees above normal, respectively.

The air temperatures aside, authorities also say ocean temperatures off the northeast coast of the United States for the first six months of the year hit a record high. The National Oceanic and Atmospheric Administration says the previous record was set in 1951. Scientists say it's unclear if the temperature rise will continue for the long term. Naturally, there's a correlation between the warming of the atmosphere and the warmer water temperatures, so this doesn't come as too much of a surprise, although it is cause for concern.

Summer officially exits the Northern Hemisphere early this weekend. The Autumnal Equinox occurs this Saturday morning, September 22, at 10:49 a.m. That's when the Sun's rays are directly above the Equator, causing "equal day and equal night" over the face of the Earth. Our weather picture should be fine the rest of the week before a front arrives Saturday night and early Sunday, triggering a few scattered showers. Dry and cool weather is expected early next week, just in time for the start of Fall.

Paul

Wonderful Weather for a Plane Ride Across Connecticut's Shoreline

Today was an ideal day for outdoor activities, whether it be a round of golf, a long walk, lunch or dinner on the patio, or even a plane ride. I took advantage of the great late-Summer weather by taking a plane ride from Sikorsky Memorial Airport in Stratford to Groton/New London airport to pick up my son, who was visiting relatives over the long holiday weekend. Pilot Morgan Kaolian, a long-time local radio traffic reporter, has been flying since 1944.

The flight took us directly over Long Island Sound and across the Connecticut shoreline, where I could easily see Milford, New Haven, Lyme, East Lyme, Waterford, and New London. Here is a video I took of our descent and landing at Groton/New London Airport.



Skies were mostly clear with a high temperature of 76 degrees at 3:36 p.m. at Sikorsky Airport, which was just about the time we landed in Groton. It was the ninth straight day without any rain in the region. The highest wind speed was 14 miles an hour from the southwest, and the average wind speed was 6.2 miles an hour. The lowest humidity level was a comfortable 43 percent at 2 o'clock.

Paul

Drought Monitor Index Labels the Northeast "Abnormally Dry"

This has been one of the best weeks of weather we've had in a long time, especially after last week's cloudiness and rain. Fair weather will continue through tomorrow before a weakening cold front arrives later tomorrow night. That may trigger an isolated shower or two late Friday night into Saturday, but that's all the moisture we'll be able to squeeze out of this system.

Although the forecast is good news for those who have outdoor activities planned this weekend, the fact is we do need the rain. I'm sure you've noticed the brown patches on lawns, and the gardens could certainly use a beneficial rain. Here is the latest Drought Index Monitor map for the Northeast as of September 11, 2012. Click the map for a larger view.

Thus far this month, we've received only about an inch (1.03") of rain through today. That's below the 1.37" normal for the period. Since January 1, the deficit is much more pronounced. We've measured 26.24" of liquid precipitation at Sikorsky Memorial Airport in Stratford, which is greater than four inches below the 30.27" normal. The next chance of any rain comes Tuesday and Wednesday of next week when an area of low pressure will affect the Northeast.

There have been just four days with measured rain this month, following a stretch of only two of 13 days with rain to close the month of August. Cumulatively, we've had six days with measured rain in nearly four weeks (26 days). August's total rainfall (3.33") was more than a half-inch below the normal (3.96") for the month. Hopefully, we can begin to make a dent in the rain deficit next week, when most of the rain comes while we are at work or school. For now, though, enjoy the sunshine!

Paul

Remembering Hurricane Donna

Today marks the 52nd anniversary of the arrival of Hurricane Donna to New England. Donna impacted most of the Caribbean Islands and every single state on the Eastern seaboard. The hurricane recorded 160 mile-an-hour winds with gusts up to 200 miles-an-hour. Hurricane Donna holds the record for retaining ‘major hurricane’ status of Category 3 or better in the Atlantic basin for the longest period of time. In fact, it was so strong that the name "Donna" has been retired.

This storm is the only one on record to produce hurricane-force winds in Florida, the mid-Atlantic States, and New England. Donna hit New England in southeastern Connecticut with sustained winds of 100 miles-an-hour, gusting to 125 to 130 miles-an-hour. It eventually moved diagonally through New England into Maine. The hurricane produced pockets of four-to-eight inches of rain as well as five to ten-foot storm surges. The storm ultimately killed 364 people and caused over $500 million in damage.

Here is a video showing the effects of the Hurricane on the Rockaways on Long Island.



Donna crossed the Florida Peninsula on September 11. Despite its path over land, the storm remained intense and reorganized when it moved back into the Atlantic Ocean. It struck eastern North Carolina and parts of South Carolina as a Category 3 storm. After reaching the ocean a third time, Hurricane Donna accelerated, crossing Long Island and then the New England region on late September 12 and early September 13 as a Category 3 hurricane on Long Island. Take a look at the front page of the Naugatuck Daily News from the previous day, September 12, 1960.



Storm surge values reached 11 feet in New York Harbor, which destroyed many piers. A resort area in Cliffwood Beach, New Jersey, saw its boardwalk and tourist attractions destroyed by the hurricane, and the area never recovered. Blue Hill Observatory in Massachusetts reported gusts to over 145 mph. The strong southwest winds associated with Donna at Chatham led to a significant deposit of salt spray, which whitewashed southwest-facing windows. Many trees and shrubs saw their leaves brown due to the salt.

From the time it became a tropical depression to when it dissipated after becoming an extratropical storm, Donna roamed the Atlantic from August 29 to September 14, a total of 17 days. Donna briefly achieved Category 5 strength while crossing the Atlantic. The highest sustained winds measured for Hurricane Donna were 160 miles-an-hour, and the lowest measured pressure was 930mb. At the time Donna struck North Carolina, its eye was unusually large, ranging from 50 to 80 miles in diameter.

Paul