Autumn Officially Arrives in the Northern Hemisphere This Weekend

The Autumnal Equinox officially arrives this Sunday, September 22, 2024, at 8:43 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 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.

Happy Autumn!

Paul

September's Full Harvest Moon Happens This Tuesday, September 17, at 10:34 p.m. EDT

The Full Moon closest to the September Equinox is called the Harvest Moon. It is unique because the Moon rises close to the same time several days in a row.

Full Moon names reflect the time of year they happen. And, true enough, the Harvest Moon graces the skies in the harvest season in the Northern Hemisphere.

There is also an astronomical reason why the Full Moon closest to the Autumnal Equinox is called the Harvest Moon.

The Moon rises about 50 minutes later each day, on average. At Full Moon, it rises as the Sun sets. In the Northern Hemisphere around the Harvest Moon, however, the difference in the time of moonrise from one day to the next is less than 50 minutes. At the latitude of New York City, the difference is around 25 minutes per day.

With successive moonrises coming around the same time of day, it may feel like there are several Full Moons in a row. Historically, the extra moonlight meant that farmers could work and harvest their crops for a longer time in the evenings. Hence, the Harvest Moon.

The Full Harvest Moon happens this Tuesday, September 17, 2024, at 10:34 p.m. EDT.

Paul

Recalling Tropical Storm Hanna 16 Years Ago

Today marks 16 years since the arrival of Tropical Storm Hanna. The storm came and went fairly quickly Saturday, September 6, 2008, delivering more than three inches of rain at Sikorsky Memorial Airport, scattered power outages, and gusty winds. It could have been a lot worse, but the storm raced through the region, arriving late Saturday afternoon and exiting during the early morning hours Sunday, September 7.

The storm brought a peak wind gust of 39 miles-an-hour and a peak wind speed of 30 miles-an-hour, sparing southwestern Connecticut any damaging or destructive winds. Perhaps the most memorable aspect of the storm was the brutal tropical humidity throughout the day, ultimately leading to the heavy downpours by late-afternoon through the evening hours.

The heaviest rain fell to our North, with parts of Northern Fairfield County receiving over a half-foot of rain. Remember, the average normal rainfall for September is 3.58 inches. 

The bands of heavy rain made traveling difficult at times, and some roadways were flooded. Mackenize Kilmartin of Fairfield sent the following photo showing minor flooding in her hometown.

 
Christine from Greenwich wrote, "Here are pictures from Todd's Point and Binney Park. Sorry if they're not great photos, but it was the best I could do without getting my camera wet."

Local residents sent the following photo of flooding on Shippan Avenue at the West Beach soccer fields under construction in Stamford. This picture was taken at 7:30 Saturday evening.

Here are some of the unofficial rainfall totals from across southwestern Connecticut from Hanna's visit:

• Woodbridge: 5.04"
• Norwalk: 4.37"
• Fairfield: 4.13"
• Greenwich: 3.93"
• Stamford: 3.62"
• Stratford: 3.55"
• Milford: 3.42"
• Bridgeport: 3.30"

The storm followed the forecast track for the most part, with the eye of the storm passing just to our East late Saturday evening and moving well to our North and East by the end of the weekend. The skies cleared quickly the following day. 

Paul

August Cooler and Wetter-Than-Normal Across Southwestern Connecticut

August was the first cooler-than-normal month at the Bridgeport climate station since November of last year. The average monthly temperature was 73.6° F, which is nearly one degree below normal (74.5°). pic.twitter.com/26LgBMXQIa

— Paul Piorek (@PaulPiorekWICC) September 1, 2024

The Bridgeport climate station recorded nearly a half-foot of precipitation (5.42") for August, which is 1.44" above the normal average. Thirteen of the 31 days (42%) featured measured rain. pic.twitter.com/PbYprc3TCv

— Paul Piorek (@PaulPiorekWICC) September 1, 2024

Paul