Monthly Archives: June 2018

What the Summer Solstice Means

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Today is the June Solstice, the first day of summer in the northern hemisphere. The new season officially began at 10:07 UTC, which is 6:07 AM 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 summer months, the northern half of the Earth is tilted toward the sun. This position allows the northern hemisphere to receive the sun’s energy at a more direct angle and produces our warmest temperatures of the year.

Since the winter solstice in December, the arc of the sun’s daily passage across the sky has been getting higher and daylight hours have been increasing. At noon today, the sun will be directly overhead at the Tropic of Cancer, its northernmost position, marking the “longest day” of the year. This observable stop in the sun’s apparent annual journey is where today’s event takes its name. Solstice is a word derived from Latin and means “the sun stands still”.

While today brings us the greatest number of daylight hours  (15 hours and 5 minutes in NYC), it is not the warmest day of the year.  The hottest part of summer typically lags the solstice by a few weeks. This is because the oceans and continents need time to absorb the sun’s energy and warm up – a phenomenon known as seasonal temperature lag.

Earth’s solstices and equinoxes. Image Credit: NASA

May 2018: Earth’s Fourth Warmest May on Record

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Our global temperature continued its upward trend last month. May 2018 marked not only the fourth warmest May on record, but also closed out the planet’s fourth warmest March to May season, known as meteorological spring in the northern hemisphere.

According to the State of the Climate report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for May – over both land and sea surfaces – was 60.04°F, which is 1.44°F above the 20th-century average. The years 2014-2018 now rank among the five warmest Mays on record.

This May also marked the 401st 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 May, some places were particularly warm, including much of Europe and North America. Here in the contiguous US, it was our warmest May ever recorded. The previous record had been in place since 1934.

Globally, the three-month period of March, April, and May was also unusually warm. NOAA reports that Earth’s average temperature for the season was 1.48°F above the 20th century average of 56.7°F. That makes it the fourth warmest such period on record.

These soaring temperatures are largely attributed to the long-term trend of human-caused climate change. ENSO-neutral conditions prevailed in May, which means there was neither an El Niño nor a La Niña in the Pacific to influence global weather patterns.

Year to date, the first five months of 2018 tied 2010 as the fourth warmest such period of any year on record. Global temperature records date back to 1880.

May 2018 was the fourth warmest May ever recorded on Earth. Credit: NOAA

Storm King Art Center Exhibition Focuses on Climate Change

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Art and science have come together to expand the public conversation on climate change  at Storm King Art Center in Orange County, NY. In an exhibition called Indicators: Artists on Climate Change, the work of seventeen artists and collectives address the diverse impacts of this critical issue.

Curated by Nora Lawrence, the exhibit is a mix of large-scale sculptures and installations spread out across the open air museum’s five-hundred acres as well as smaller pieces displayed in an indoor gallery.

Credit: Mary Mattingly/Storm King

Notable among the various projects is Mary Mattingly’s installation, Along the Lines of Displacement: A Tropical Food Forest. This stand of palm trees imported from Florida offers visitors a glimpse of what the landscape of upstate New York might look by the end of the century when the average temperature is expected to increase by 7.2°F (4°C) if global warming continues unabated.

Credit: Justin Brice Guarigila/Storm King

Another piece that stands out in Storm King’s bucolic setting is Justin Brice Guarigila’s We Are the Asteroid.  The orange colored, solar-powered LED highway message sign – the sort usually seen flashing information about dangerous situations – displays three-line ecological aphorisms by philosopher Timothy Morton. These include the piece’s moniker as well as things like “Danger: Anthropocentrism” and “Warning: Hurricane Human”.

Credit: Hara Woltz/Storm King

Embracing the science of climate change is Hara Woltz’s “Vital Signs”. In this interactive piece, a working weather station is encircled  by nine cylinders (a reference to the shape of ice-core tubes) that present the idea of albedo and melting sea ice. The top of each cylinder gets darker as a viewer moves around the circle. More specifically, the lighter area decreases by 13% per cylinder reflecting the predicted decrease in Arctic sea ice per decade relative to the 1981-2010 average. The cylinders also progressively get taller, referencing sea level rise. Data from the weather station is displayed in real time on Storm King’s website.

Other exhibiting artists include David Brooks, Dear Climate, Mark Dion, Ellie Ga, Allison Janae Hamilton, Jenny Kendler, Maya Lin, Alan Michelson, Mike Nelson, Steve Rowell, Gabriela Salazar, Rebecca Smith, Tavares Strachan, and Meg Webster.

The exhibit is on view through November 11, 2018.

How Hail Forms

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The thunderstorms of spring and summer are notorious for their powerful winds and heavy rain. However, when strong enough, they can also produce hail.

Hailstones start off as water vapor that is lifted high into the atmosphere by the updraft of a thunderstorm. Rising into cooler air, it condenses and forms water droplets. Once these liquid droplets reach a level where the temperature is below freezing, they turn into tiny ice crystals. Overtime, they get larger as other water droplets freeze to them on contact, forming layers like an onion.  Once a hailstone gets too heavy for the updraft, it falls to the ground.

The stronger the updraft of a storm, the longer a hailstone remains suspended, and the larger it can grow. For a ball of ice to be considered a hailstone, according to the AMS, it has to measure at least 5mm in diameter.

The largest hailstone ever recorded in the US was found in Vivian, South Dakota on June 23, 2010. It measured 7.9 inches in diameter and weighed 1.94 pounds. The updraft supporting it would have had to exceed 150 mph.

Needless to say, hail can cause serious damage to people and property.

Weather Lingo: June Gloom

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For most people in the US, the month of June is associated with warm temperatures and abundant sunshine. For parts of coastal California, however, it is a month known for cloudy and relatively cool conditions. This regional phenomenon called “June Gloom” is the result of the interaction of several natural elements, including geography, ocean currents, and weather patterns.

With the California Current running south along the coast from the Gulf of Alaska, the water in the area is cold. Ocean temperatures in the region usually hover in the upper 50s to low 60s during the summer, cooling the air that flows over it.

Another significant factor is the temperature inversion aloft created by the North Pacific High, a semi-permanent area of high pressure. This is part of a larger planetary circulation of air known as a Hadley cell, a current of high altitude air traveling poleward from the tropics. As the air cools, it descends around 30N latitude. It compresses and warms as it sinks, making the air aloft warmer than the cold, moist air at the surface. Since air temperatures normally decrease with height, this situation acts like a cap on the cool air below and prevents it from rising any higher.

When the air under the inversion layer, known as the marine layer, is cooled to the point where the moisture condenses, an expansive sheet of low level stratus clouds form.  The region’s prevailing westerly winds, as well as the sea-breeze circulation that often develops during the summer months, carries these clouds inland.  While they create overcast conditions and some light drizzle, the clouds do not produce any significant rain. They also tend to dissipate by the afternoon as the land heats up.

The thickness and inland extent of the marine layer clouds depend on the strength of the high-pressure system. A stronger high will thin the clouds and keep them confined to the coast. A weaker high with allow the clouds to thicken and move further inland. Separated by only a few miles, the cloud-covered coast can be significantly cooler than sunny areas further east.

These conditions are most common in June, but are not necessarily limited to the month. They have been known to develop in May and last on and off through August. The monikers for these events include “May Gray”, “No Sky July”, and “Fogust”.  However, high pressure usually builds over southern California in July, decreasing the impact of the marine layer or eliminating it altogether.

“June Gloom” clouds along west coast. Credit: NWS/UCSD

May 2018: Fifth Warmest on Record in NYC

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May felt like a weather roller-coaster in New York City this year. Highs ranged from a cool 54°F to a record warm 92°F. However, with 20 out of 31 days posting above average readings, the warmth won out in the end. The city’s mean temperature for the month was 66.9°F, which is 4.5°F above average. That makes May 2018 the fifth warmest May on record in NYC.

On the precipitation side of things, May was below normal despite producing 13 days with measurable rainfall.  In all, 3.53 inches of rain was measured in Central Park. Of that total, 0.58 inches fell during a severe thunderstorm that swept through the city on May 15. The month, on average, brings the New York City 4.19 inches of rain.

Credit: The Weather Gamut

 

Names for the 2018 Atlantic Hurricane Season

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Today is the first day of the Atlantic Hurricane Season. Although one named storm, Alberto, already formed this year, the season officially runs from June 1 to November 30.

Since 1950, each tropical storm or hurricane to form in the Atlantic has been given a unique name. They come from a set of six rotating lists produced by the World Meteorological Organization. A name is retired only when a storm was particularly noteworthy – causing a large number of fatalities or an extraordinary amount of damage. Some notable retired Atlantic Basin storm names include: Andrew, Harvey, Irma, Irene, Katrina, Maria, and Sandy. The names for this year’s storms are listed below.

Credit: NOAA