Tag: weather

Ice Chunks Are Fascinating To Look At, But Can Cause Serious Flooding

Mohawk River ice jam: Giant chunks of ice washed up on the shore of the Mohawk River.

The weather has been all over the spectrum in the last few weeks.

Record-breaking frigid temperatures and wind chills kicked off 2018, followed by temperatures into the 50s and 60s last week.

Temperatures plummeted to start off this week, and central Pennsylvania woke up Wednesday to a few inches of fresh snowfall.




A gradual warmup is expected into this weekend, with highs in the 50s predicted. The upcoming warmup has meteorologists keeping an eye on what the warmer weather could mean for ice jams in rivers and streams.

It’s something we’re going to have to keep an eye on,” said Craig Evanego, a meteorologist with National Weather Service.

Evanego explained the warmer temperatures could enable ice jams to break free and move down rivers and streams.

He added that some areas in the northern part of the state are already experiencing ice jam issues on localized streams thanks to elevated water levels.

Frozen river ice: Frozen river ice melts in layers as chunks wash up on shore.

With the gradual warmup, we’ll see if things will begin to thaw and move down the (Susquehanna) river,” Evanego said.

Senior meteorologist Alex Sosnowski with AccuWeather said that thanks to the persistent cold, pretty thick layers of ice have been able to form.

Along with fluctuating temperatures, Sosnowski said river levels are a little higher, adding that another rain event is expected from Monday to Wednesday next week.

Mohawk River ice jam: Jams can cause floods, which threaten buildings near the banks.

Sosnowski explained a major risk with ice jams is that when they break free, they send a surge of water down the river, which can cause flooding in unprotected areas.

Sosnowski expected that levee systems should be able to protect against any flooding caused by ice packs, and said unprotected areas are at the most risk for flooding.

Sosnowski encouraged those who want to go out and observe ice packs to do so carefully, as they can break away and begin drifting downstream at any time.

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Video Captures Moment When Kid Is Nearly Hit By Lightning

An Argentine mom filming her 12-year-old son fooling around with an umbrella ended up capturing his brush with death as a lightning bolt struck just feet away.

The video shows the unidentified pre-teen standing under a roof drainpipe, with water pouring out onto the umbrella.

Seconds later, he walks out into a garden in the city of Posadas, in the northeastern Argentine province of Misiones.

Then out of nowhere, a powerful bolt of lightning strikes down just steps in front of the boy — causing a nearby fence to erupt in flames.




The boy’s frightened mom, Carolina Kotur, shrieked and quickly dropped her phone.

It was morning, I was with my daughter in the room calming her, because she is scared of lightning,” Kotur told local media.

Then the lady who works in my house told me that my son was walking in the rain and I started filming because I was making a joke, and right next to him the lightning struck. Thank God nothing happened to him.”

Others in the region were not so fortunate during the fierce storm, Central European News reported.

 

Brothers Sinforiano Venialgo Vazquez, 43, and Simon Venialgo Vazquez, 41, were killed when lightning struck near their home in the Paraguayan town of San Pedro del Parana — 68 miles from where the young boy was nearly hit by the bolt.

The cause of death in both cases was electrocution, though no further details were available, according to the report.

Lightning strikes reportedly killed animals in the Santa Rosa area, on the Argentine side of the Parana River, the outlet reported.

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Scientists Study Winter Storms Involving Thundersnow To Pinpoint Where Heavy Snowfalls May Occur

It’s been more than 30 years—during the Blizzard of 1978 to be exact—since Neil Stuart saw “thundersnow,” a weather phenomenon featuring the unusual combination of thunder, lightning and snow.

The National Weather Service (NWS) meteorologist was 10 years old, living near Boston. The storm—which he says “is famous in meteorological circles” and influenced his career path—dumped 27 inches of snow on the ground over two days.

The heaviest snow, however, came during a six-hour thundersnow storm that delivered one foot of snow over a six hour period.

Seeing thundersnow come down is “like watching a time-lapse movie of the snow building up, because it falls so quickly,” Stuart says.




 

Thunder and lightning during a snowstorm is different from a run-of-the-mill snowstorm; it is extremely rare—fewer than 1 percent of observed snowstorms unleash thundersnow, according to a 1971 NSW study.

But recorded observations of the phenomenon date back to 250 B.C., say ancient Chinese records translated in 1980 by atmospheric scientist Pao-Kuan Wang, now of the University of Wisconsin–Madison.

Today, researchers are interested in thundersnow for its predictive value.

According to Patrick Market, an associate professor of atmospheric science at the University of Missouri, a 30-year study of snowfall found that when lightning is observed during a snowstorm, there is an 86 percent chance that at least 15 centimeters of snow will fall within 113 kilometers of the flash.

Researchers are trying to determine the combo of atmospheric conditions required to create thundersnow to help them better predict heavy snowfall.

Which they define as at least 20 centimeters falling at a rate of 7.5 to 10 centimeters per hour—and issue warnings about hazardous weather before it hits, giving people time to prepare, take cover and get off the road.

By the time the lightning flashes during a thundersnow-storm, it is often already too late to prepare local residents for the whiteout on the way.

If we’re talking about the observation of thundersnow,” Market says, “the predictive value is on the order of minutes to hours.

In the U.S. thundersnow is most likely to form in mountainous regions like the Rockies as well as in the vicinity of comparatively warm and large bodies of water such as the Great Lakes.

Snow requires a cold environment, adequate moisture to form clouds, and rising air; thundersnow makes an appearance when a fourth ingredient is added: thermal instability, which is created by the addition of relatively warm air.

Market last month joined a team of storm-chasing University of Illinois at Urbana–Champaign researchers using various radars to examine what takes place inside storm clouds to cause snowfall.

The team is surveying atmospheric conditions in several locations in Indiana, Illinois and Wisconsin.

A field mill, a device that measures electric fields near the ground, will be used to determine whether there is an accumulation of charged ice particles in the clouds above.

The team next year plans to fly into snowstorms in NWS planes and drop parcels containing thermometers, barometers and other devices that, like weather balloons, will measure temperature on their way down.

If the team encounters thundersnow during its study, it may be able to confirm the conditions needed to produce it, making such icy tempests easier to forecast.

With some lead time, [be it] hours or even a day or two,” Stuart says, “we can see a big storm and predict which areas will see extreme snowfall.

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Sky Watching Tips And Tricks For Cold Northern Nights

For much of the contiguous United States this winter has been marked by perpetual ice, snow as well as the now infamous polar vortex.

Such conditions might make even the most committed stargazer think twice before venturing outdoors.

Stepping outside to enjoy a view of the constellation Orion, Jupiter or even just the waxing moon these frosty nights takes only a minute or two, but if you plan to stay outside longer, remember that enjoying the starry winter sky requires protection against the cold temperatures.




The best garments are a hooded ski parka and ski pants, both of which are lightweight and provide excellent insulation. And remember your feet.

Two pairs of warm socks in loose-fitting shoes are quite adequate; for protracted observing on bitter-cold nights wear insulated boots.

Reach for the binoculars

In weather like this, one quickly will realize the advantage of using a pair of good binoculars over a telescope.

A person who attempts to set even a so-called “portable” scope up in bitter temperatures or blustery winds might give up even before he or she got started.

But binoculars can be hand-held and will produce some quickly magnified images of celestial objects before rushing back inside to escape the frigidity.

Transparency

In their handy observing guide, “The Stars” (Golden Press, N.Y.), authors Herbert Zim and Robert Baker write that “the sky is never clearer than on cold, sparkling winter nights.

“It is at these times that the fainter stars are seen in great profusion. Then the careful observer can pick out dim borderline stars and nebulae that cannot be seen when the sky is less clear.

What Zim and Baker were referring to is sky transparency, which is always at its best during the winter season. That’s because Earth’s atmosphere is not as hazy because it is less moisture laden.

Cold air has less capacity to hold moisture, therefore the air is drier and thus much clearer as opposed to the summer months when the sky appears hazier.

But this clarity can also come at a price.

Seeing through the twinkles

If you step outside on one of those “cold, sparkling nights” you might notice the stars twinkling vibrantly.

This is referred to as scintillation, and to the casual observer looking skyward, they might think of such a backdrop as the perfect night for an astronomer, but it isn’t.

This is because when looking skyward, skywatchers are trying to see the sky through various layers of a turbulent atmosphere.

Were we to train a telescope on a star, or a bright planet like Mars, what we would end up with is a distorted image that either seems to shake or quiver or simply “boils” to the extent that you really can’t see very much in terms of any detail.

Forecasting sky conditions

If you own a telescope, you don’t need to wait for balmy summer nights to get good views. Usually, a few days after a big storm or frontal passage, the center of a dome of high pressure will build in to bring clear skies and less wind.

And while the sky might not seem quite as “crisp” or “pristine” as it was a few days earlier, the calming effect of less winds will afford you a view of less turbulent and clearer images through your telescope.

More comfortable nights ahead

If you plan on heading out on a cold winter’s night — and if you’re doing it while under a dome of high pressure — the fact that there is less wind means not only potentially good seeing, but also more comfort viewing conditions.

The end of winter is in sight though. The Northern Hemisphere is officially halfway through the winter season and milder, more comfortable nights are within reach.

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How Do Hurricanes Form? A Step-By-Step Guide.

Whenever hurricane season arrives in the Atlantic Ocean — typically between June and November — a bunch of meteorological terms get hurled around.

Tropical storm. Tropical depression. Category 3 hurricanes. Category 4 hurricanes.

So what’s the difference between all these types of weather events? One way to understand this is to walk through the different stages of a hurricane, step by step.

We’ll use Hurricane Irma, which started out as a wave off the African coast and went on to pound several Caribbean before it hit Florida as a Category 4 storm, as an example:




1) Tropical disturbance: A hurricane in the Atlantic Ocean typically begins life as a lowly “tropical disturbance” — defined as organized thunderstorm activity that stretches at least 100 miles across and maintains its identity for more than 24 hours.

During the summer, these disturbances often start as storms moving westward off the coast of Africa in what are known as “tropical waves.”

If meteorologists think a tropical disturbance may develop further, they’ll designate it as an “investigative area,” or invest.

Irma became a disturbance off the Cape Verde Islands in late August, with forecasters keeping close watch as it headed west.

2) Tropical depression or cyclone: Under the right conditions, a tropical disturbance can develop further and start to spin around a low-pressure center. Once that happens, it’s classified as a “tropical cyclone” or “tropical depression”:

For a tropical depression to form, conditions have to be just right: The water has to be warm enough to fuel the system, with temperatures of 80°F or hotter.

There needs to be enough moisture in the lower and middle part of the atmosphere. Local winds also have to be arranged so that they allow the depression to spin — too much wind shear can tear an aspiring tropical cyclone apart.

3) Tropical storm: This is the next stage. When the pressure in the center of the tropical depression drops, air rushes in, creating strong winds.

If the system strengthens and wind speeds rise past 39 mph, the system is dubbed a “tropical storm” and is given a name.

That’s what happened to Irma on August 30, as it picked up speed in the far Eastern Atlantic and intensified.
The US National Hurricane Center makes the call for when a tropical depression officially becomes a tropical storm.

It relies on data from islands and buoys as well as from reconnaissance aircrafts that fly into the storms to measure wind speed.

4) Hurricane: Tropical storms can intensify quickly if they pass over a region of especially warm water and don’t face much wind shear. As that happens, the pressure in the center drops even further and the winds really pick up.

The system gets rounder and often forms a clearly defined “eye.” Here’s Irma on Wednesday:

When the winds reach sustained speeds of 74 mph or more, the storm system is classified as a hurricane. Hurricanes are categorized according to the Saffir-Simpson Scale based on their wind speed and propensity for damage.

Irma was a Category 5 as of September 5 with wind speeds of 185 miles per hour. That’s serious — major hurricanes can do structural damage to buildings, take down trees, and cause widespread flooding.

Side note: The fact that you need especially warm water here explains why hurricanes only form in the Atlantic during the late summer months.

It also helps explain why global warming may lead to stronger hurricanes, although this gets complicated, since climate change can also affect wind shear that suppresses hurricanes.

5) Back down to tropical storm: Hurricanes can also weaken, however, as they move over land (or cooler water) and no longer have warm, moist air to fuel them.

Once wind speeds drop below 75 miles per hour, the hurricane gets downgraded to a tropical storm — and, later on, a “post-tropical cyclone” as it degrades further.

For example, Hurricane Hermine in 2016 was downgraded to a tropical storm not long after it made landfall in Florida in September.

But then Hermine moved back over the Atlantic Ocean and hit record-warm ocean temperatures there, gathering to hurricane strength again.

It’s worth emphasizing that even tropical cyclones that aren’t hurricanes can still do a great deal of damage by bringing torrential rain, dangerous surf, beach erosion, high winds, and flooding.

In 2012, “superstorm” Sandy was technically no longer a hurricane when it hit the East Coast, but it still proved devastating to the New York and New Jersey coasts.

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Cargo Ships Are Creating Sea Lightning

Thunderstorm aficionados, if you really want to see some action then get yourself aboard a cargo ship.

A new study has shown that lightning strikes occur nearly twice as often above busy shipping lanes than in the regions to either side.

It turns out the belching fumes from ship exhausts are helping to trigger extra lightning.

While analysing data from the Worldwide Lightning Location Network, a web of sensors around the world that track lightning strikes, researchers noticed nearly straight lines of lightning strikes across the Indian Ocean and South China Sea.




By comparing the lightning data with maps of ships’ exhaust emissions they were able to show that there were nearly twice as many lightning strikes along the main shipping routes between Sri Lanka and Sumatra, and between Singapore and Vietnam.

This enhanced level of lightning was visible at least as far back as 2005.

Writing in Geophysical Research Letters, the researchers explain how the ship exhaust fumes add more particles to the air, which encourages more cloud droplets to form.

Because the cloud droplets are smaller and lighter than they would otherwise be they travel higher into the atmosphere and are more likely to reach the freezing line, so creating more ice particles.

Collision between ice particles causes storm clouds to electrify, and lightning is the atmosphere’s way of neutralising the built-up electric charge.

It’s one of the clearest examples of how humans are actually changing the intensity of storm processes on Earth through the emission of particulates from combustion,” said Joel Thornton, from the University of Washington, in Seattle, the lead author of the study.

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Pass it on: New Scientist

Green Flash: Sunset Phenomenon

green-flash

A green flash, which occurs more commonly at sunset but can also occur at sunrise is a phenomenon in which part of the sun can be observed suddenly and briefly changing color.

It usually lasts only a second or two which is why it is referred a flash as the sun changes from red or orange at sunset, for example.

The green flash is viewable because refraction bends the light of the sun. The atmosphere acts as a weak prism, which separates light into various colors.




When the sun’s disk is fully visible above the horizon, the different colors of light rays overlap to an extent where each individual color can’t be seen by the naked eye.

As the sun sinks into the Pacific, its last light seems to glow green. This “green flash,” caused by light refracting in the atmosphere, is rarely seen.

But Nigella Hillgarth, the director of the Birch Aquarium at the Scripps Institution of Oceanography in San Diego, got lucky one night.

green-flash

I often work late and have developed the habit of taking photos of the incredible sunsets over the Pacific from the Aquarium,” Hillgarth said.

One evening, I was snapping away and caught the green flash as it appeared. I was hoping for a green flash, but was very excited when one actually happened and I caught it!

When the sun starts to dip below the horizon the colors of the spectrum disappear one at a time, starting with those with the longest wavelengths to those with the shortest. At sunrise, the process is reversed, and a green flash may occur as the top of the sun peeks above the horizon.

green-flash

It is a primarily a green flash because more green light gets through and therefore is more clearly seen.

Sometimes, when the air is especially clear, enough of the blue or violet light rays make it through the atmosphere, causing a blue flash to be visible. However, green is the most common hue reported and captured in photos.

Most green flashes fall into two categories: inferior mirage flashes and mock mirage flashes.

green-flash

Inferior mirage flashes, which accounts for about two-thirds of all green flash sightings, are oval and flat and occur close to sea level and when the surface is warmer than the air above.

Mock mirage flashes occur higher up in the sky and when conditions on the surface are colder than the air above. The flashes appear to be thin, pointy strips being sliced from the sun.

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Global Warming Will Make Our Winter Colder

global warming

According to the National Aeronautics and Space Administration (NASA), the 10 warmest years on record have occurred since 1997.

And the National Atmospheric and Oceanographic Administration (NOAA) reports that recent decades have been the warmest since at least around 1000 AD, and that the warming we’ve seen since the late 19th century is unprecedented over the last 1,000 years.

“You can’t tell much about the climate or where it’s headed by focusing on a particularly frigid day, or season, or year, even,” writes Eoin O’Carroll of the Christian Science Monitor.




“It’s all in the long-term trends,” concurs Dr. Gavin Schmidt, a climatologist at NASA’s Goddard Institute for Space Studies.

Most scientists agree that we need to differentiate between weather and climate. The NOAA defines climate as the average of weather over at least a 30-year period.

So periodic aberrations like the harsh winter storms ravaging the Southeast and other parts of the country this winter do not call the science of human-induced global warming into question.

The flip side of the question, of course, is whether global warming is at least partly to blame for especially harsh winter weather.

winter

As we pointed out in a recent EarthTalk column, warmer temperatures in the winter of 2006 caused Lake Erie to not freeze for the first time in its history.

This actually led to increased snowfalls because more evaporating water from the lake was available for precipitation.

But while more extreme weather events of all kinds from snowstorms to hurricanes to droughts are likely side effects of a climate in transition, most scientists maintain that any year-to-year variation in weather cannot be linked directly to either a warming or cooling climate.

Even most global warming skeptics agree that a specific cold snap or freak storm doesn’t have any bearing on whether or not the climate problem is real.

snow storm

One such skeptic, Jimmy Hogan of the Rational Environmentalist website writes, “If we are throwing out anecdotal evidence that refutes global warming we must at the same time throw out anecdotal evidence that supports it.”

He cites environmental groups holding up Hurricane Katrina as proof of global warming as one example of the latter.

If nothing else, we should all keep in mind that every time we turn up the thermostat this winter to combat the cold, we are contributing to global warming by consuming more fossil fuel power.Until we can shift our economy over to greener energy sources, global warming will be a problem, regardless of how warm or cold it is outside.

Until we can shift our economy over to greener energy sources, global warming will be a problem, regardless of how warm or cold it is outside.

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Cloud Atlas Leaps Into 21st Century With A Whole New Species Of Clouds

Cloud Atlas may be best known as a big-budget 2012 movie, staring Tom Hanks, but the International Cloud Atlas is a guide that every meteorologist in the world can turn to when looking at the clouds we see in the sky.

Established in 1939 by the World Meteorological Organization (WMO) and last updated in 1986, this invaluable resource has now been moved into the digital realm, so that it is available to us all, and it adds a dozen new cloud types. Both naturally-occurring and human-caused – to its lexicon of weather terms.

Clouds are classified in a way very similar to what’s used in biology – genera for the overarching classes, based on their height and thickness (cirrus, cumulus, stratus, etc).

Species for specific types under those broad classes (fractus, congestus, etc), varieties that describe the organization and transparency of the clouds.

And then supplementary features, which are smaller clouds associated with and attached to larger clouds, and accessory clouds that are smaller clouds associated with larger clouds, but are mostly separate from them.

So, let’s meet these new cloud types!




Volutus

Volutus

Volutus is a new species of cloud that encompasses the various roll clouds. These form as long, horizontal tubes, detached from any other clouds in their vicinity, which are caused by differences in wind speed and direction between the surface and higher up (aka wind shear).

Asperitus

asperatus

Formerly known as undulatus asperatus, when the supplemental feature Asperitus shows up, it’s almost like looking at waves on the surface of the water, but from a vantage point under the water. The Atlas separates this from “undulatus” clouds, since undulatus are much more organized (often into bands).

Cavum

Cavum

Cavum is now the formal name of what’s been called a “fallstreak cloud” or “hole punch cloud”.

This supplemental feature is caused when ice crystals are introduced into a thin cloud comprised of super-cooled water droplets, usually due to an aircraft passing through the cloud on takeoff or landing.

The water droplets remain liquid well below freezing, since there is nothing present for them to freeze onto. With the sudden appearance of the ice crystals, the water droplets in the vicinity all rush in – creating a clear spot in the cloud where they freeze and grow the crystals into snowflakes, which then fall out of the sky.

Murus

Murus

A Murus, or wall cloud, is a supplemental feature that takes the shape of bank of cloud that lowers from the base of a supercell, is associated with strong updrafts, and can indicate the presence, or impending development, of a tornado.

Fluctus

Fluctus

These supplemental features, now called Fluctus, are widely known as Kelvin-Helmholtz waves or Kelvin-Helmholtz instability. These features are caused by the winds above the cloud top blowing faster than the winds inside the cloud.

This difference in speed (aka velocity shear) creates vortices, resulting in the top of the cloud being pulled upward into these wave forms.

For more amazing cloud pictures, head over to the International Cloud Atlas image gallery.

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Monster Hail Storm Could Be On The Rise If Global Warming Continues

There is much uncertainty about the effects of anthropogenic climate change on the frequency and severity of extreme weather events like hailstorms, and subsequent economic losses, while this is also relevant information for the design of climate policy.

Few studies conducted indicate that a strong positive relation exists between hailstorm activity and hailstorm damage, as predicted by minimum temperatures using simple correlations.

This relation suggests that hailstorm damage may increase in the future if global warming leads to further temperature increase.




This study estimates a range of Tobit models of relations between normalized insured hailstorm damage to agriculture and several temperature and precipitation indicators for the Netherlands. Temporal dynamics are explicitly modeled.

A distinction is made between damage costs for greenhouse horticulture and outdoor farming, which appear to be differently affected by variability in weather. ‘Out of sample’ forecast tests show that a combination of maximum temperatures and precipitation predicts hailstorm damage best.

hail storm

Extrapolations of the historical relations between hailstorm damage and weather indicators under climate change scenarios project a considerable increase in future hailstorm damage.

Our estimates show that by 2050 annual hailstorm damage to outdoor farming could increase by between 25% and 50%, with considerably larger impacts on greenhouse horticulture in summer of more than 200%.

The economic implications of more hailstorm damage for, and adaptation by, the agricultural and insurance sectors are discussed.

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Pass it on: New Scientist