Fall Nor’easter Transitions to Sub-Tropical Storm Melissa

The nor’easter that has been battering the northeast coast of the US for several days transitioned to Sub-Tropical Storm Melissa on Friday. It is now the 13th named storm of the Atlantic hurricane season.

Lingering offshore since Wednesday, states from the mid-Atlantic to New England have been feeling its impacts in the form of strong winds, heavy rain, and coastal flooding. On Friday, its sustained winds were measured up to 60 mph.

Classified as subtropical, Melissa is a hybrid between a tropical storm and a regular low-pressure system. A tropical system is fueled by the latent heat released by the evaporation of ocean water while a regular storm is powered by the temperature contrast between air masses. Hybrids are able to access both energy sources.

The National Hurricane Center expects Melissa to become post-tropical and move further out to sea over the weekend.

Subtropical Storm Melissa swirling off the coast of New England. Credit: NOAA

What Causes the Smell of Rain?

Rain is often associated with particular smells. But, rain itself is odorless. So, where do these aromas come from?

The distinctive scent that lingers in the air after a rainstorm is known as petrichor. It is the product of two reactions that occur when rainwater hits the ground. Its main driver is a soil-dwelling bacteria called actinomycetes. These microorganisms thrive in moist conditions, but as the soil dries out, they produce spores. These are then released into the air by the moisture and force with which the rain hits the ground. This happens at the same time the rainwater is mixing with oils that were secreted by plants onto nearby rocks and soil during times of dryness. Together these reactions produce the musky petrichor smell, which is particularly strong after a long dry spell. The term was coined in 1964 by two Australian scientists, Isabel Joy Bear and RG Thomson. They derived it from the Greek words, “petra” meaning stone and “ichor”, the term used to describe the blood of the gods in ancient mythology.

A different, and often more pungent, rain smell is associated with thunderstorms. After the powerful electric charge of a lightning bolt splits the oxygen and nitrogen molecules in the atmosphere, they often recombine as nitric oxide. This, in turn, interacts with other atmospheric chemicals to form ozone (O3). When people say they can “smell the rain coming”, this is the scent they detect as it often arrives in the wind ahead of an approaching storm.

Credit: freepik

October Begins with Weather Whiplash in NYC

Autumn is a transitional season where a few warm days still pop up as cooler temperatures gradually take hold. This week in New York City, however, it felt like we jumped from mid-July to late October in only one day.

On Wednesday, the temperature soared to a sweltering 93°F, setting a new record high for the date. The previous record of 90°F had been in place since 1927. Then, the temperature plummeted overnight. On Thursday, the mercury only made to 63°F.  While not a record-breaker, it was the coolest day the city has seen in months.

The normal high for this time of year in the Big Apple is around 70°F.

Credit: The Weather Gamut

Record Breaking October Heat in NYC

The season officially changed to autumn last week, but it felt more like summer in New York City on Wednesday.

The temperature in Central Park soared to 93°F, setting a new record high for the date. The previous record of 90°F had been in place since 1927. Wednesday also marked the second warmest October day ever recorded in the Big Apple. Only October 5, 1941, was warmer when the temperature hit an unseasonably sultry 94°F.

This type of heat is unusual for NYC in October. In fact, this was only the sixth time temperatures ventured into the 90s during the month since record-keeping began in 1869.

At this point in October, the normal high in the city is 69°F. But with a stubborn ridge of high pressure sitting over the region, warm air is flowing further north than it normally would at this time of year.  It is also important to note that as our climate changes, record warm days are occurring more often and the autumn season as a whole is heating up.

Credit: The Weather Gamut

September 2019: 8th Driest September on Record for NYC

September 2019 felt like a weather roller coaster in New York City. Highs ranged from a balmy 89°F to a chilly 67°F. But, with 18 out of 30 days posting above-average readings, the warmth won out in the end. The city’s mean temperature for the month was 70.4°F, which is 2.4°F above average.

In terms of precipitation, September was a month for the record books. The city only received 0.95 inches of rain in Central Park, marking its eighth driest September on record. It was also the second month in a row to deliver below-average rainfall in NYC. On average, the Big Apple gets 4.28 inches of rain for the month.

Autumn is Heating Up Across the US

Autumn is a transitional season. It is generally a time when the heat of summer fades away and the chill of winter gradually returns. But, as our climate changes, the season is heating up.

Across the contiguous United States, autumn temperatures have increased an average of 2.5°F over the past fifty years, according to Climate Central. The western part of the country has seen the fastest seasonal increase, with Reno, NV warming 7.7°F.  Las Vegas, NV, and El Paso, TX have each seen a rise of more than 5°F since 1970.

These warmer temperatures may feel like a summer bonus for some, but they also bring a number of negative impacts. Less frost-free days means the allergy season is extended and disease-carrying pests like mosquitos and ticks are able to live and thrive longer. Warmer temperatures also drive up energy bills, as people with air conditioning units use them longer into the season. This in turn, if they are powered by fossil fuels, adds even more heat-trapping greenhouse gases to the atmosphere.

Wildlife is also feeling the effects of a warming fall. The timing of when fruits ripen, for example, is being skewed from its “normal schedule”. In turn, this is impacting the once well-synced patterns of animal behaviors such as bird migration and hibernation.

Looking ahead, as greenhouse gas emissions continue to increase, so too will the temperature and its associated impacts.

Credit: Climate Central

Celebrating Eight Years of Writing about Weather and Climate

It is hard to believe, but today marks the eighth anniversary of The Weather Gamut.

Initially begun as a way to deepen and share my knowledge about weather and climate change, this blog has allowed me to expand on my interests and concerns in ways that I never thought possible. This past year, I gave a variety of presentations on creative climate communication and was invited to share my climate-related artwork in several exhibitions around the world.

Producing this blog has been an interesting journey that has taught me a great deal about the science of weather and climate as well as the art of writing. It has also put me in touch with many wonderful people working in this fascinating field. I am grateful for all their support and encouragement.

As always, thank you for reading!

The Science Behind the Autumnal Equinox

Today is the Autumnal Equinox, the first day of fall in the northern hemisphere. The new season officially began at 7:50 UTC, which is 3:50 AM Eastern Daylight Time.

The astronomical seasons, as opposed to the meteorological seasons, are a product of Earth’s axial tilt – a 23.5° angle – and the movement of the planet around the sun. During the autumn 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 summer solstice in June, the arc of the sun’s apparent daily passage across the sky has been sinking and daylight hours have been decreasing. 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”.

Transitioning from summer to winter, autumn is also a season of falling temperatures. According to NOAA, the average high temperature in most US cities drops about 10°F between September and October.

Earth’s solstices and equinoxes. Image Credit: NASA

Climate Week NYC Focuses on “A Race We Can Win”

Climate Week NYC begins on Monday. This annual event is taking place alongside the UN Climate Action Summit, the theme of which is “A Race We Can Win. A Race We Must Win.”

Organized by The Climate Group, the week-long event brings together leaders from a variety of sectors, including government, business, and non-profit organizations, to discuss solutions to climate change. Their overall goal is to accelerate climate action and limit global warming to 1.5°C.

Public events to raise awareness and support of the summit’s mission are scheduled all around the city. They range in style from panel discussions and seminars to concerts and exhibitions. One early event taking place this Saturday is the “Our Future Festival”, which has been organized by the NYC Chapter of the Climate Reality Project.  For the full program of events, go to the Climate Week website.

Credit: The Climate Group

Earth Posts 2nd Warmest August and 2nd Warmest June-August Season on Record

Our global temperature continued its upward trend last month. August 2019 marked not only Earth’s second warmest August, but also closed out the planet’s second warmest June-August 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 August – over both land and sea surfaces – was 61.76°F, which is 1.66°F above the 20th-century average. This August also marked the 416th 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 June, July, and August – meteorological summer in the northern hemisphere – was also unusually warm. NOAA reports that Earth’s average temperature for the season was 1.67°F above the 20th century average of 60.1°F. That makes it the second warmest such period on record. It is also important to note that nine of the ten warmest June-August periods have all occurred since 2009.

While heat dominated most of the planet this August, some places were particularly warm, including Europe, Africa, and parts of Hawaii and Alaska. For the contiguous US as a whole, August 2019 tied August 1955 as the 13th warmest on 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 eight months of 2019 were the third warmest such period of any year on record. At this point, it is very likely that 2019 will finish among the top five warmest years ever recorded. Global temperature records date back to 1880.

Credit: NOAA