News / Science & Technology

Study: Jet Traffic Near Airports Can Trigger Snowfalls

Artificially-induced snow creates circular hole in cloud layer

A hole-punch cloud over Alabama
A hole-punch cloud over Alabama

Multimedia

Audio

Scientists have found that aircraft flying through a layer of cold-temperature clouds can trigger a snowfall that normally wouldn’t occur.

The artificially-induced snow creates a great circular hole in the cloud layer. "Hole-punch" clouds are so rare and unique-looking, some witnesses have mistaken them for UFOs.

“Just do a search on hole-punch clouds on the web and you’ll see fabulous examples of what look like layer clouds with circular holes in them,” says Andy Heymsfield, senior scientist at the National Center for Atmospheric Research in Colorado and lead scientist on the study.



Three and a half years ago, he wasn’t attempting to link aircraft to hole-punch clouds. Instead, he and his colleagues were trying to understand how ice crystals form and develop in clouds.

Accidental discovery

“We had a research aircraft equipped with almost every imaginable probe for measuring the structure or the internal properties of these clouds,” he says.

One of these instruments was a cloud radar, a special device that can peer inside clouds just as an x-ray peers inside our body. About six months after their field work, a scientist studying the radar images stumbled across something very interesting, something he couldn’t explain.

"He passed through a very strange band of snow falling to the ground," says Heymsfield. "It was just fairly isolated. He noticed a very narrow line, but a long line, of precipitation that seemed to be coming out from a cloud deck up high."

There were no meteorological reasons why snow would be falling only along a linear path instead of over a wide area. So he turned to the other instruments to explain the phenomenon.

"On the aircraft we had digital photography looking forward and down so I could actually see what looked like snow reaching the ground and what looked like a line - a hole, canal or a channel in the cloud layer above," says Heymsfield.

Mysterious snowfall

The snowfall had hollowed out a long channel in the cloud. But there was still no explanation for what caused the line of snow, although Heymsfield had a hunch.

Reviewing the flightpaths of planes flying in and out of Denver International Airport, he found the snowfall followed the path a  turboprop airplane had flown earlier that day.

“And in natural clouds you can have liquid water at temperatures in clouds down to as far as minus 40 degrees C before the droplets sort of automatically freeze,” he says.

In perfect conditions, aircraft can cool a cloud enough to generate those ice crystals.

The spinning propeller expands and cools the air behind it by as much as 30 degrees centigrade. Similar cooling occurs with jet aircraft. The pressure reduction over the wing which gives it lift also causes the air to expand and cool.

“Ice crystals upon which the ice can grow are introduced into a cloud, then the ice crystals will grow, the droplets will evaporate and you can generate snow.”

Airport connection

The next question was: can this happen around airports where there are a lot of commercial jet flights?  

“We used satellite imagery to document that around airports with heavily trafficked areas conditions are just right fairly commonly- a winter month, maybe 10 or 15 percent of the time," he says. "When it does happen, ice crystals would be generated upwind of an airport, which could then drift over the airport and lead to more deicing operation”

Heymsfield says this phenomenon is not likely to affect global climate. Fellow cloud scientist, Patrick Chuang, agrees. But the associate professor of Earth and Planetary Sciences at the University of California, Santa Cruz, says the effect may skew climate records.

“I think the importance is in the fact that we really rely on airports to provide long-term records of weather, which then are used for things like climate change detection and just understanding how climate is changing," says Chuang. "It’s not like any cloud is conducive to this. I think it’s still not going to be a very commonplace event.”

You May Like

Turkey: No Ransom Paid for Release of Hostages Held by IS Militants

President Erdogan hails release of hostages as diplomatic success but declines to be drawn on whether their release freed Ankara's hand to take more active stance against insurgents More

Audio Sierra Leone Ebola Lockdown May Be Extended

Lockdown, which started Friday, aims to allow health workers to locate hidden Ebola patients, educate others on how to avoid the deadly disease More

US Pivot to Asia Demands Delicate Balancing Act

As the tumult in the Middle East distracts Obama, shifting American focus eastward appears threatened More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Natural Gas Export Plan Divides Maryland Towni
X
Deborah Block
September 21, 2014 2:12 PM
A U.S. power company that has been importing natural gas now wants to export it. If approved, its plant in Lusby, Maryland, would likely be the first terminal on the United States East Coast to export liquefied natural gas from American pipelines. While some residents welcome the move because it will create jobs, others oppose it, saying the expansion could be a safety and environmental hazard. VOA’s Deborah Block examines the controversy.
Video

Video Natural Gas Export Plan Divides Maryland Town

A U.S. power company that has been importing natural gas now wants to export it. If approved, its plant in Lusby, Maryland, would likely be the first terminal on the United States East Coast to export liquefied natural gas from American pipelines. While some residents welcome the move because it will create jobs, others oppose it, saying the expansion could be a safety and environmental hazard. VOA’s Deborah Block examines the controversy.
Video

Video Fears Ebola Outbreak ‘Beyond Our Capability to Contain’

Each day brings with it new warnings about the deadly Ebola outbreak already blamed for killing more than 2,600 people across West Africa. And while countries and international organizations like the United Nations are starting to come through on promises of help for those most affected, the unprecedented speed with which the virus has spread is raising questions about the international response. VOA's Jeff Seldin has more from Washington.
Video

Video Difficult Tactical Battle Ahead Against IS Militants in Syria

The U.S. president has ordered the military to intensify its fight against the Islamic State, including in Syria. But how does the military conduct air strikes in a country that is not a U.S. ally? VOA correspondent Carla Babb reports from the Pentagon.
Video

Video Iran, World Powers Seek Progress in Nuclear Talks

Iran and the five permanent members of the U.N. Security Council plus Germany, known as the P5 + 1, have started a new round of talks on Iran's nuclear program. VOA State Department correspondent Pam Dockins reports that as the negotiations take place in New York, a U.S. envoy is questioning Iran's commitment to peaceful nuclear activity.
Video

Video Alibaba Shares Soar in First Day of Trading

China's biggest online retailer hit the market Friday -- with its share price soaring on the New York Stock Exchange. The shares were priced at $68, but trading stalled at the opening, as sellers held onto their shares, waiting for buyers to bid up the price. More on the world's biggest initial public offering from VOA’s Bernard Shusman in New York.
Video

Video Obama Goes to UN With Islamic State, Ebola on Agenda

President Obama goes to the United Nations General Assembly to rally nations to support a coalition against Islamic State militants in Iraq and Syria. He also will look for nations to back his plan to fight the Ebola virus in West Africa. As VOA White House correspondent Luis Ramirez reports, Obama’s efforts reflect new moves by the U.S. administration to take a leading role in addressing world crises.
Video

Video Migrants Caught in No-Man's Land Called Calais

The deaths of hundreds of migrants in the Mediterranean this week has only recast the spotlight on the perils of reaching Europe. And for those forunate enough to reach a place like Calais, France, only find that their problems aren't over. Lisa Bryant has the story.
Video

Video Westgate Siege Anniversary Brings Back Painful Memories

One year after it happened, the survivors of the terror attack on Nairobi's Westgate Shopping Mall still cannot shake the images of that tragic incident. For VOA, Mohammed Yusuf tells the story of victims still waiting for the answer to the question 'how could this happen?'
Video

Video Militant Assault in Syria Displaces Thousands of Kurds

A major assault by Islamic State militants on Kurds in Syria has sent a wave of new refugees to the Turkish border, where they were stopped by Turkish border security. Turkey is already hosting about 700,000 Syrian refugees who fled the civil war between the government and the opposition. But the government in Ankara has a history of strained relations with Turkey's Kurdish minority. Zlatica Hoke reports Turkey is asking for international help.
Video

Video Whaling Summit Votes to Uphold Ban on Japan Whale Hunt

The International Whaling Commission, meeting in Slovenia, has voted to uphold a court ruling banning Japan from hunting whales in the Antarctic Ocean. Conservationists hailed the ruling as a victory, but Tokyo says it will submit revised plans for a whale hunt in 2015. Henry Ridgwell reports from London.
Video

Video A Dinosaur Fit for Land and Water

Residents and tourists in Washington D.C. can now examine a life-size replica of an unusual dinosaur that lived almost a hundred million years ago in northern Africa. Scientists say studying the behemoth named Spinosaurus helps them better understand how some prehistoric animals adapted to life on land and in water. The Spinosaurus replica is on display at the National Geographic museum. VOA’s George Putic has more.
Video

Video Iraqi Kurdistan Church Helps Christian Children Cope find shelter in churches in the Kurdish capital, Irbil

In the past six weeks, tens of thousands of Iraqi Christians have been forced to flee their homes by Islamic State militants and find shelter in churches in the Kurdish capital, Irbil. Despite U.S. airstrikes in the region, the prospect of people returning home is still very low and concerns are starting to grow over the impact this is having on the displaced youth. Sebastian Meyer reports from Irbil on how one church is coping.


Carnage and mayhem are part of daily life in northern Nigeria, the result of a terror campaign by the Islamist group Boko Haram. Fears are growing that Nigeria’s government may not know how to counter it, and may be making things worse. More

AppleAndroid