Monthly Archives: December 2019

The Chances for a White Christmas

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The Holiday Season is here and many people are dreaming of a White Christmas. The likelihood of seeing those dreams come true, however, is largely dependent on where you live.

According to NOAA, a White Christmas is defined as having at least one inch of snow on the ground on December 25th. In the US, the climatological probability of having snow for Christmas is greatest across the northern tier of the country. Moving south, average temperatures increase and the odds for snow steadily decrease.

Here in New York City, the historical chance of having a White Christmas is 11%. This low probability is largely due to the city’s proximity to the Atlantic Ocean and its moderating influence on the temperature.

The snowiest Christmas on record for the Big Apple, according to the NWS, took place in 1909 when seven inches of snow was reported in Central Park.

This year, with temperatures forecast to be in the mid-40s on the big day, the city’s already minimal chance for snow has largely melted away.

Snow or no snow, The Weather Gamut wishes you a very Happy Holiday Season!

Source: NOAA

The Science Behind the Winter Solstice

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Today is the December solstice, the first day of winter in the northern hemisphere. The new season officially begins at 11:19 PM EST.

The astronomical seasons, which are different than meteorological seasons, are produced by the tilt of the Earth’s axis – a 23.5° angle – and the movement of the planet around the sun. During the winter months, the northern half of the Earth is tilted away from the sun. This position means the northern hemisphere receives the sun’s energy at a less direct angle and brings us our coolest temperatures of the year.

Since the summer solstice in June, the arc of the sun’s apparent daily passage across the sky has been dropping southward and daylight hours have been decreasing. Today, it will reach its southernmost position at the Tropic of Capricorn (23.5° south latitude), marking the shortest day of the year. This observable stop is where today’s event takes its name. Solstice is derived from the Latin words “sol” for sun and “sisto” for stop.

Soon, the sun will appear to move northward again and daylight hours will slowly start to increase. Marking this transition from darkness to light, the winter solstice has long been a cause for celebration across many cultures throughout human history.

Earth’s solstices and equinoxes. Image Credit: NASA

November 2019: Earth’s Second Warmest November on Record

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Our global temperature continued its upward trend last month with November 2019 marking the second warmest November ever recorded on this planet. Only November 2015 was warmer. The month also closed out Earth’s second warmest September to November season on record.

According to the State of the Climate Report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for November – over both land and sea surfaces – was 56.86°F, which is 1.66°F above the 20th-century average. This November also marked the 419th 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.

The three-month period of September, October, and November – meteorological autumn in the northern hemisphere – was also unusually warm. NOAA reports that Earth’s average temperature for the season was 1.69°F above the 20th century average of 57.1°F. That makes it the second warmest such period on record. It is also important to note that the ten warmest September-November periods have all occurred since 2005, with the five warmest taking place in the last five years.

While heat dominated most of the planet this November, some places were particularly warm, including Central Europe, eastern Russia, northern Canada, and most of Alaska. For the contiguous US as a whole, November 2019 ranked in the middle third of the historical record.

These soaring temperatures are largely attributed to the long-term trend of human-caused climate change. As greenhouse gases continue to spew into the atmosphere, global temperatures are expected to continue to rise.

Year to date, the first eleven months of 2019 were the second warmest such period of any year on record. At this point, it is very likely that 2019 will finish as the second or third warmest year ever recorded. Global temperature records date back to 1880.

Credit: NOAA

COP 25: UN Climate Talks Come to Disappointing End

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After extended negotiations, the UN Climate Change Conference in Madrid, Spain, known as COP 25, came to a disappointing end on Sunday. Delegates from nearly 200 countries failed to reach a consensus on how to finalize the rules and processes needed to translate the spirit of the historic Paris Agreement into action.

Years in the making, the 2015 Paris Agreement set the target of holding global warming to 2°C (3.6°F) above pre-industrial levels and urged countries to pursue an even tighter cap of 1.5°C (2.7°F). To achieve this ambitious goal, almost 200 countries submitted individual voluntary emissions reduction plans known as nationally determined contributions (NDCs). But when added up, the current collection of NDCs, which vary widely in ambition, will miss the 2°C goal. In fact, they would allow for a 3.2°C (5.76°F) rise in our global temperature. For reference, we have already seen a 1°C (1.8°F) increase since 1880.

The main goals of COP 25 were to push for more substantial NDC commitments, set the rules for a carbon trading market, and establish a financial provision to compensate developing countries for “loss and damages” associated with global warming. But in the end, the delegates were only able to agree on vague language supporting the basic essence of the Paris Agreement. They cited the “urgent need” to reduce emissions but pushed off all major decisions to next year.

This unconstructive outcome is particularly notable as the global temperature continues to rise and the resulting impacts – such as more intense storms, wildfires, and sea-level rise – are becoming more apparent. It is also a stark contrast to the fact that Greta Thunberg, the teenage climate activist, was named Time Magazine’s Person of the Year.

The Paris Agreement, although ratified in record time, is a fragile accord. All commitments are voluntary and vulnerable to the political will of individual governments – both now and in the future. Moreover, there are no penalties for those who do not live up to their promises.

In terms of US involvement, President Trump, who has called climate change a “hoax”, has already announced his intent to withdraw from the international accord. The agreement, however, was written to ensure that countries could not begin the formal withdrawal process until four years after the accord officially went into effect. Consequently, the US cannot truly withdraw until November 4, 2020. That is one day after the next presidential election. As such, the role that the US will ultimately play in global climate action rests with voters.

The Madrid meeting was the 25th session of the Conference of the Parties (COP) to the U.N. Framework Convention on Climate Change (UNFCCC). The next conference (COP 26) will take place in November 2020 in Glasgow, Scotland.

Credit: UN

Weather and Health: SAD

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Autumn and winter, with their crisp temperatures, are favorite seasons for many. But for others, the decreasing daylight hours can bring on a condition known as Seasonal Affective Disorder (SAD).

According to the Mayo Clinic, SAD is a “subtype of depression that comes and goes with the seasons” and is most common in fall and winter. Its exact cause is not fully understood, but researchers say a reduction of sunlight can disrupt the production of serotonin and melatonin – chemicals in the brain that regulate mood and sleep patterns. SAD symptoms include low spirits, lack of energy, difficulty concentrating, and changes in both sleep and eating patterns.

SAD is typically found in places that are far from the equator where daylight is at a minimum in the winter months. A report by the American Academy of Family Physicians says about 6% of the US population suffers from some degree of SAD, with most cases occurring in Alaska.

The most common treatment for SAD is light therapy. This involves sitting in front of a special lamp that gives off a light that is similar to natural sunshine. It has been shown to trigger the brain chemicals that regulate mood. The more serious cases of SAD could require advanced talk-therapy or even medication.

While everyone can feel a little “blue” once in a while, SAD is characterized by a prolonged feeling of depression. It can be a serious condition and should be diagnosed by a medical professional.

Weather affects mood. Credit: hercampus

Talking About Art and Environmental Policy at AGU

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The 100th Annual Fall Meeting of the American Geophysical Union (AGU) is taking place this week in San Francisco, CA. Marking its centennial, the conference, which is the largest gathering of earth and space scientists in the world, aims to “celebrate the past and inspire the future”.

Thrilled to be a part of it, I will be giving a presentation titled The Power of Perception: Art’s Influence on US Environmental Policy Past and Present. It looks at the role art has played in helping to build the political will behind several landmark environmental policies over the years and how it can help with climate change communication today.

From the Yosemite Land Grant of 1864 to the present, images have helped give the public, and the policymakers they elected, a new way to relate to and understand the issues of their time. In many cases, images mobilized public concern that helped drive legislation. The publication of photos of the Cuyahoga River fire of 1969 in Time Magazine, for example, helped spur the passage of the Clean Water Act and the creation of the EPA in the 1970s.

While environmental concerns have changed over the years, so too has technology and the way we relate to images. As such, this presentation also poses questions about what form of art will reach the most people and motivate them to speak up on climate change today.

Credit: AGU

Gallery Talk: “Weather the Weather” at NY Hall of Science

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Art and science have come together at the New York Hall of Science to highlight the fascinating world of weather. In a group exhibition titled Weather the Weather, artworks of various mediums explore the different ways we understand and experience the forces of nature.

Curated by Marnie Benney, this SciArt Initiative exhibition features the work of twenty-one artists from around the world. Honored to be one of them, images from my American Glaciers: Going, Going, Gone and Wildfires series are on display.

If you are in the area, Ms. Benney will lead a gallery tour and talk with several of the artists on Saturday, December 7 from 2 to 3:30 PM. To attend, please register via Eventbrite.

The exhibition will be on view through January 10, 2020 at The New York Hall of Science, 47-01 111th Street, Queens, NY. For hours and directions, visit www.nysci.org

Credit: NYSci/SciArt

First Snowfall of the Season for NYC

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New York City saw its first snowfall of the 2019-2020 winter season on Monday.

According to the NWS, 1.5 inches of snow was measured in Central Park. While not a blockbuster event, it was exciting to see the flakes fill the air. With all the holiday lights and decorations on display, the snow also added to the city’s festive atmosphere.

The timing of this first snowfall was about normal for the Big Apple. On average, the first flakes of the season are seen in early to mid-December. Our earliest first snow event on record was on October 21, 1952, and our latest was January 29,1973. New York City typically gets 4.8 inches of snow in December and  25.8 inches for the entire winter season.

Credit: Melissa Fleming

From Snow to Freezing Rain: Why Winter Precipitation Can Take Several Forms

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The winter season can produce various types of precipitation – rain, freezing rain, sleet, or snow. The form we see at the surface depends on the temperature profile of the lower atmosphere.

All precipitation starts out as snow up in the clouds.  But, as it falls toward the Earth, it can pass through one or more layers of air with different temperatures.  When the snow passes through a thick layer of warm air – above 32°F – it melts into rain.  If the warm air layer extends all the way to the ground, rain will fall at the surface.  However, if there is a thin layer of cold air – below 32°F – near the ground, the rain becomes supercooled and freezes upon impact with anything that has a temperature at or below 32°F.  This is known as freezing rain.  It is one of the most dangerous types of winter precipitation, as it forms a glaze of ice on almost everything it encounters, including roads, tree branches, and power lines.

Sleet is a frozen type precipitation that takes the form of ice-pellets. Passing through a thick layer of sub-freezing air near the surface, liquid raindrops are given enough time to re-freeze before reaching the ground. Sleet often bounces when it hits a surface, but does not stick to anything.  It can, however, accumulate.

Snow is another type of frozen precipitation.  It takes the shape of six-sided ice crystals, often called flakes.  Snow will fall at the surface when the air temperature is below freezing all the way from the cloud-level down to the ground.  In order for the snow to stick and accumulate, surface temperatures must also be at or below freezing.

When two or more of these precipitation types fall during a single storm, it is called a wintry mix.

Precipitation type depends on the temperature profile of the atmosphere. Credit: NOAA

November 2019: Unusually Cold and Dry in NYC

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November felt like a wild ride of weather in New York City. Highs ranged from an unseasonably warm 71°F to a chilly 34°F. But, with 20 out of 30 days posting below-average readings, the cold won out in the end. The month also produced our first freeze of the season and two record cold overnight lows. Overall, the city’s mean temperature for November was 43.9°F, which is 3.8°F below average.

On the precipitation side of things, the month was unusually dry. Only nine days delivered measurable rainfall, which added up to a paltry 1.95 inches in Central Park. New York City, on average, gets 4.02 inches for the month.