A Look at the Science Behind the Spring Equinox

Today is the Vernal Equinox, the first day of spring in the northern hemisphere. The new season officially begins at 21:58 UTC, which is 5:58 PM Eastern Daylight Time.

Our astronomical seasons are a product of the tilt of the Earth’s axis – a 23.5° angle – and the movement of the planet around the sun. During the spring months, the Earth’s axis is tilted neither toward nor away from the sun. This position distributes the sun’s energy equally between the northern and southern hemispheres.

Since the winter solstice in December, the arc of the sun’s apparent daily passage across the sky has been getting higher and daylight hours have been increasing. Today, the sun appears directly overhead at the equator and we have approximately equal hours of day and night. The word “equinox” is derived from Latin and means “equal night”.

As a transitional season, spring is a time when the chill of winter fades away and the warmth of summer gradually returns. The most noticeable increases in average daily temperature, however, usually lag the equinox by a few weeks.

Earth’s solstices and equinoxes. Image Credit: NASA

A Look at Rainbows and their Legendary Pots of Gold on this St Patrick’s Day

According to Irish folklore, a pot of gold can be found at the end of a rainbow. In reality, however, it is impossible to locate the terminus of this optical phenomenon.

Refraction and reflection inside a raindrop. Credit: Met Office

For a rainbow to form, rain has to be falling in one part of the sky while the sun is out in another. The water droplets in the air act like prisms that refract and reflect the sunlight, revealing the colors of the visible spectrum. Red is refracted the least and is always on the top of a single bow while blue is on the bottom. Since we only see one color from each drop, it takes a countless number to produce a rainbow.

A double rainbow is seen when the light reflects twice inside the raindrops. Since each reflection weakens the intensity of the light, the second bow appears dimmer. The order of the colors is also reversed, with blue on top and red on the bottom.

That said, these colorful arcs are not physical entities that can be approached. No matter how close they appear to be, they are always tantalizingly out of reach. Nevertheless, most people consider seeing one to be a treasure with no gold required.

With a little luck, you can spot a rainbow if you face a moisture source – rain or mist from a waterfall – while the sun is at your back.

Happy Saint Patrick’s Day!

Rainbow and faint second rainbow form after a rainstorm in Bermuda. Credit: Melissa Fleming

A Spring Preview Melts March Snow in NYC

The calendar says March, but it felt more like May in New York City on Friday.

The temperature soared to 75°F in Central Park, missing the record high by just 2°F. But, with the mercury only dropping to 49°F at night, it did tie the record warm low temperature for the date that was set in 1913.

The normal high and low temperatures for this time of year in NYC are 49°F and 35°F, respectively.

With below normal temperatures dominating the beginning of March, this sudden warm up felt like weather whiplash. Just a week earlier, there was snow on the ground with snowmen dotting the landscape in parks across the city.

But, as with most things that go up, they must also come back down. Cooler conditions are expected to return over the weekend.

What a difference a week can bring: the same snowman in Central Park one week apart. Credit: Melissa Fleming

 

Flashback Facts: NYC’s Great Blizzard of 1888

On this day in 1888, one of the worst snowstorms on record hit New York City. Here is a look back at some of the facts from that historic storm.

Snow fills the street and sidewalk on Park Place in Brooklyn, after the Blizzard of 1888. Credit: NOAA.

  • 21 inches of snow was measured in Central Park, the 4th largest snowstorm on record for the city
  • Wind gusts reached 80mph, causing blizzard conditions
  • Snowdrifts reached as high as 30 feet in parts of the city.
  • The storm shut down transportation systems and left people confined to their homes for days.
  • It took NYC 14 days to fully recover from the storm.
  • As result of the paralyzing impacts of this blizzard, the city moved all overhead wires underground.

Source: NOAA

A Snowy Start to March in NYC

March rolled into New York City this year like a lion.

Below average temperatures and snow have been the prevailing weather stories all week. In fact, the first four days of March produced more snow than the city has seen all winter. To date this month, 10.4 inches of snow has been reported in Central Park. On average, March typically brings the city a total of 3.9 inches.

This winter, overall, has been below par in terms of snow in NYC. Including the record snowfall in November, the city has seen 20.5 inches of snow so far.  The season usually brings the Big Apple 25.8 inches of snow, with February producing the biggest storms.

“Encounter 2019”: An Art and Science Exhibition on Climate Change

Art and science are coming together in Durham, England to help expand the public conversation on climate change. In a group exhibition titled Encounter 2019 at Ustinov College at Durham University, artworks of various mediums along with scientific research posters explore the diverse impacts of this pressing issue.

Curated by Miyoko Yamashita McGregor, the overall theme of the show investigates the interaction between climate change, nature, and society. It features the work of over 30 contributors, including several scientists who presented aspects of their research as artwork. Two examples from this category are The Heat is Piling Up and A Story of Climate Change. Both are artful and engaging displays of scientific data.

The Heat is Piling Up, by Professor Glenn McGregor, Principal of Ustinov College, and Professor Camila Caiado, is a colorful column of stripes that shows how the average temperature in Durham has been increasing since record keeping began there in 1850. (Image far left)

A Story of Climate Change by Professor Dave Roberts is a digital x-ray image of a sediment core collected from the Hebridean Continental Shelf. It was taken as part of the NERC Britice-Chrono project, which is attempting to reconstruct a picture of the advance and retreat of the British-Irish Ice Sheet during the last glacial cycle. (Image near left).

Honored to be included in the exhibition, several pieces from my Under Glass series and my ongoing project, American Glaciers: Going, Going, Gone are also on display.

Encounter 2019 is the second of three Encounter exhibits planned by the University. It will be on view from March 2 – 14, 2019 at Ustinov College, Sheraton Park, Durham University, Durham DH1 4FL, UK.

Icebergs break off from Portage Glacier, AK. Credit: Melissa Fleming

February 2019: A Weather Roller Coaster in NYC

February was a month of wild temperature swings in New York City. Producing several days of weather whiplash, highs ranged from a frigid 21°F to an unseasonably warm 65°F. However, in the end, these extremes balanced each other out. The city’s mean temperature for the month was 36.2°F, which is only 0.9°F above average.

In terms of precipitation, rainfall was also slightly above average with twelve of the month’s 28 days posting measurable rainfall. In total, Central Park reported 3.19 inches of rain, which is 0.10 inches above normal.

Snowfall, on the other hand, was scarce. February is usually the city’s snowiest month on the calendar, but Central Park only received 2.6 inches of snow this year. Of that total, most it fell during storms that produced a wintry mix of precipitation. On average, February produces 9.2 inches of snow in the city.

February was a weather roller coaster in NYC. Credit: The Weather Gamut

Wild Winds Whip Through NYC

Powerful winds battered the northeastern United States on Monday. More than 900 reports of wind damage were posted across the region.

Here in New York City, a high wind warning was issued by the NWS. Gusts reached as high as 58mph at LaGuardia Airport in Queens.

The strong winds downed trees around the five boroughs, tore awnings from restaurants, and even caused a partial scaffolding collapse at a building on Manhattan’s upper east side.  The tempest also prevented a cruise ship, the Norwegian Gem, from docking in the city. Loaded with passengers, gale force winds kept it sitting off the coast for hours. Significant airport delays and cancellations were also reported.

The reason for these blustery conditions, like most weather events, is about location. The region was wedged between an area of low pressure to the northeast and an area of high pressure to the west. As they moved closer together, a strong pressure gradient developed and the winds blew faster and faster.

Strong winds caused damage around NYC. Credit: NYPD 19th pct.

Weather Lingo: The Beaufort Wind Force Scale

From a light breeze to a strong gale, wind speed can be described in numerous ways. All of which are categorized on the Beaufort Wind Force Scale.

Developed in 1805 by Sir Francis Beaufort, an officer in the UK’s Royal Navy, the scale is an empirical measure of wind speed. It relates wind speed to observed conditions at sea and over land instead of using precise measurements. Simply put, it allows a person to estimate wind speed with visual clues.

Initially, it was only used at sea and was based on the effect the wind had on the sails of a frigate – the most common type of ship in the British Navy at the time. By the mid-1800s, the scale was adapted to also reflect a certain number of anemometer rotations – a device that measures wind speed.

In the early 20thcentury, most ships transitioned to steam power and the scale descriptions were changed to reflect the state of the sea instead of the sails. Around the same time, the scale was extended to land observations. For example, the amount of leaf, branch, or whole tree movement is a visual indicator of the force of the wind.

Today, the scale has 13 categories (0 -12), with 0 representing calm winds and 12 being hurricane force. It is in use in several countries around the globe.

In the US, when winds reach force 6 or higher, the NWS begins issuing advisories and warnings for different environments. For marine areas, force 6-7 winds would prompt a small craft advisory, force 8-9 would warrant a gale wind warning, and a wind reaching force 10-11 would call for a storm warning. Force 12 would constitute a hurricane-force wind warning. On land, winds expected to reach force 6 or higher would cause a high wind warning to be issued.

If the winds are connected to a tropical cyclone, they would be measured on the Saffir-Simpson scale. The same type of special circumstances would also hold for a tornado, which would be measured on the Enhanced Fujita Scale.

The Beaufort Wind Force Scale. Credit: Isle of Wight Weather Ctr

January 2019: Earth’s Third Warmest January on Record

Our global temperature continued its upward trend last month with January 2019 tying 2007 as the third warmest January ever recorded on this planet. Only January 2016 and 2017 were warmer.

According to a report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for the month – over both land and sea surfaces – was 55.18°F. That is 1.58°F above the 20th-century average. January was also the 409th consecutive month with a global temperature above its long-term norm. That means the last time any month posted a below average reading was December 1984.

While heat dominated most of the planet this January, some places were particularly warm, including large parts of Asia and Australia. The contiguous US was also above average for the month, ranking among the warmest third of the period of record.

Coming on the heels of 2018 – Earth’s fourth warmest year on record – these soaring temperatures are largely attributed to the long-term trend of human-caused climate change. In fact, the ten warmest Januaries have all occurred since 2002.

Global temperature records date back to 1880.

Credit: NOAA