Monthly Archives: October 2019

How Wildfires Get Named

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Wildfires, like major storms, are named for ease of communication and historical reference. But unlike hurricane names which are chosen from a pre-determined list each season, wildfires are labeled on a rolling basis.

According to CalFire, a wildfire is named as soon as it is reported. The moniker is usually selected by the dispatcher who takes the call or the initial first responders on the scene. Driven largely by geography, the names reflect a landmark such as a canyon, creek, or road, near where the fire started. For the sake of simplicity, they often tend to be one word titles. Although efficient, this can lead to some ominous or misleading names such as the “Witch Fire” of 2007 in San Diego or the “Easy Fire” that is currently burning in Simi Valley, CA.

If a fire occurs repeatedly in the same place, it will get a name and number such as “Bear Fire 2” or “Canyon Fire 3”.

While this may seem like a free-wheeling way to do things, the National Interagency Fire Center offers guidelines for the best practices in naming a fire. They advise against using the names of people, companies, or private property. They also discourage the use of “deadman” in any fire name.

Regardless of how arbitrarily selected or innocuous a name may sound, fires will ultimately be remembered for the destruction they cause.

Kincade Fire 2019. Credit: KTVU

How the Santa Ana and Diablo Winds Help Wildfires Spread

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The Diablo and Santa Ana winds are notorious for exacerbating wildfires in northern and southern California, respectively.

These strong winds blow warm, dry air across the region at different times of the year, but mainly occur in the late autumn. They form when a large pressure difference builds up between the Great Basin – a large desert that covers most of Nevada  – and the California coast. This pressure gradient funnels air downhill and through mountain canyons and passes toward the Pacific. Squeezing through these narrow spaces, the wind is forced to speed up. According to the NWS, they can easily exceed 40 mph.

Originating in the high desert, the air starts off cool and dry. But as it travels downslope, the air compresses and warms. In fact, it warms about 5°F for every 1000 feet it descends. This dries out the region’s vegetation, leaving it susceptible to any type of spark. The fast-moving winds then fan the flames of any wildfires that ignite.

These infamous zephyrs are named for the places from which they tend to blow. The Santa Ana Winds are named for Santa Ana Canyon in Orange County. The Diablo Winds take their moniker from Mount Diablo, which sits northeast of San Francisco.

Credit: Insider Inc

Weather Report: Exploring the Atmosphere Through Art

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The weather is a hot topic in the arts these days, moving from the background of landscape imagery to the main subject. This transition is the focus of the exhibition, Weather Report at The Aldrich Contemporary Art Museum in Ridgefield, CT.

Curated by Richard Klein, the exhibit features a wide array of artists influenced by the workings of our atmosphere. Some examples that stood out to me include Kim Keever’s “Clouds” that were created with various pigments in a tank of water and Sarah Bouchard’s “Weather Box”, which makes music from weather data. The sculptures of weather map graphics by Bigert and Bergström, a Swedish art duo, also caught my eye as they explore the way weather has influenced historical events. Overall, the exhibition aims to highlight the sky as a place where the aesthetic, the political, and the scientific co-exist and inform each other.

The show is on view through March 29, 2020. For more information, visit: http://aldrichart.org

Bigert and Bergström’s “The Russian Campaign, 1812.” Photo: Melissa Fleming

September 2019: Earth’s Warmest September on Record

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Our global temperature continued its upward trend last month. September 2019 tied September 2015 as the warmest September ever recorded on this planet.

According to NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for the month – over both land and sea surfaces – was 60.71°F. That is 1.71°F above the 20th-century average. September also marked the 417th 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.

Furthermore, the ten warmest Septembers have all occurred since 2005, with the last five years being the five warmest on record.

While heat dominated most of the planet this September, some places were particularly warm, including Alaska, the southeastern United States, and large parts of Asia and Canada. For the contiguous US as a whole, the month tied September 2015 as the second warmest September on record.

With ENSO neutral conditions prevailing in the Pacific, 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 nine 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 among the top five warmest years on record. Global temperature records date back to 1880.

September 2019 was Earth’s warmest September on record. Credit: NOAA

Fall Nor’easter Transitions to Sub-Tropical Storm Melissa

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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?

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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

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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

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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

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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.