Measuring Mount Everest -- With Ever More Precision

Mount Everest is unquestionably the world’s highest mountain – but just how high, exactly, is it? Toting the latest technology, a team of climbers is heading for the rooftop of the world to find out.

Everest and the Rongbuk Monastery in Nepal
Everest and the Rongbuk Monastery in Nepal
Thomas Jüngling

There is no reliable fixed point anywhere on earth. Everything is in flux. The sea moves back and forth in a regular ebb and flow. The moon's gravitational pull also influences the earth's crust, which rises and falls daily by as much as 60 centimeters. Even the North and the South Pole move a couple of centimeters every year.

Despite this, technicians working for the Nepalese government have been charged with determining the exact height -- to within a few centimeters -- of Mount Everest. Helping them are mountain climbers and some very high-tech equipment.

Using very simple means, James Nicolson was the first to measure the altitude of the world's highest mountain 150 years ago. He recorded 8,840 meters – just over 29,000 feet. That was astonishingly close to the present widely-accepted figure, which is 8,848.40 meters, but which is, however, disputed by some. The technicians presently measuring Everest are due to present their results to the Nepalese government in two years' time.

Their most important tool is the Global Positioning System (GPS), which involves two dozen satellites that orbit the Earth and send radio signals. The satellites are placed in such a way that four of them cover every part of the planet at any given time. Since their exact positions are known, GPS receivers like the Leica Geosystems SmartRover can calculate their own positions from the data and exact time.

Since these receivers only weigh a few kilograms, they can be brought up to Everest's peaks with relative ease. Measurements are made every two seconds for about an hour. As the GPS signals are not disturbed on their way through the ionosphere and the troposphere, measurement technicians can combine the data measured on the mountain with data from the GPS receivers on the ground.

Beams and prisms

Also in use are tachymeters that measure both horizontal and vertical angles as well as distance, and beam infrared rays that reflect off prisms placed on the mountain peaks. Distance can be measured by the amount of time it takes the beam to reach the prism and return.

Another tool used by the technicians are planes equipped with an airborne scanner that scans the mountain. Some have a sensor that takes pictures of the mountain, operating like a camera – but with a lot higher resolution. Points on the pictures can only be exactly defined if the flying altitude at the time the picture was taken can be precisely determined.

The geodatists have to take numerous influences and conditions into account, starting with base level -- the usual reference point being sea level. This can, however, vary. For example, around Sri Lanka the Indian Ocean level measures 105 meters lower; to the northeast of Australia, it's nearly 80 meters higher, which is why technicians calculate an average theoretical sea level for every point on earth.

The earth's gravitational field isn‘t the same everywhere either, and that also has to be taken into account in the measurements. This is not a reading taken on the mountain. "To do that, you'd have to use a gravimeter and they are very heavy. The National Geographic Institute (IGN) in Paris tried twice to get one up a mountain and failed both times," says Farouk Kadded, a product manager at Leica Geosystems who also leads expeditions on France's Mont Blanc.

When used in the mountains, GPS receivers, tachymeters and sensors are extremely sensitive to weather conditions. Temperatures on Mount Everest are around minus 40 degrees Celsius, and atmospheric pressure around 326 millibars – about a third of normal pressure on the ground. This too has to be taken into account in calculating measurements.

There are myriad of other areas that could lead to miscalculation. For example, how high the snow cover is on the mountain has to be subtracted from the result: the point is to calculate the elevation of the naked rock. If a geodatist on the mountain were to jam his GPS device mounted on a pole seven centimeters into the snow, measurement results would be false. Radars and spectrometers can measure the thickness of snow by emitting waves of different lengths.

In view of all this high tech effort, the question poses itself: What for? For one thing, spectacular projects of this type enable the manufacturers of various devices to get a lot of publicity, says Kadded. But also "because we can test the reliability of our Leica Geosystems GPS devices."

"On Mont Blanc, every two years we measure not only the height at the top but a lot of other points to determine the form and volume of the ice cap and to be able to trace the changes over time," says Kadded.

Such data is crucial, he says, to climate researchers, meteorologists, glaciologists -- and nivologists: scientists who study snow.

Read the original article in German

Photo - Steve Hicks

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The Food Truck, A Sign That The White And Wealthy Are Moving In

In San Diego, California, a researcher tracked how in the city's low-income neighborhoods that have traditionally lacked dining options, when interesting eateries arrive the gentrification of white, affluent and college-educated people has begun.

Balboa Park Spring Fling Food Truck festival

San Diego Food Trucks via Facebook
Pascale Joassart-Marcelli

SAN DIEGO — Everybody, it seems, welcomes the arrival of new restaurants, cafés, food trucks and farmers markets.

What could be the downside of fresh veggies, homemade empanadas and a pop-up restaurant specializing in banh mis?

But when they appear in unexpected places – think inner-city areas populated by immigrants – they're often the first salvo in a broader effort to rebrand and remake the community. As a result, these neighborhoods can quickly become unaffordable and unrecognizable to longtime residents.

An appetite for gentrification

I live in San Diego, where I teach courses on urban and food geographies and conduct research on the relationship between food and ethnicity in urban contexts.

In recent years, I started to notice a pattern playing out in the city's low-income neighborhoods that have traditionally lacked food options. More ethnic restaurants, street vendors, community gardens and farmers markets were cropping up. These, in turn, spurred growing numbers of white, affluent and college-educated people to venture into areas they had long avoided.

This observation inspired me to write a book, titled The $16 Taco, about how food – including what's seen as "ethnic," "authentic" or "alternative" – often serves as a spearhead for gentrification.

Take City Heights, a large multi-ethnic San Diego neighborhood where successive waves of refugees from places as far away as Vietnam and Somalia have resettled. In 2016, a dusty vacant lot on the busiest boulevard was converted into an outdoor international marketplace called Fair@44. There, food vendors gather in semi-permanent stalls to sell pupusas, lechon (roasted pig), single-sourced cold-brewed coffee, cupcakes and tamarind raspado (crushed ice) to neighborhood residents, along with tourists and visitors from other parts of the city.

Informal street vendors are casualties.

A public-private partnership called the City Heights Community Development Corporation, together with several nonprofits, launched the initiative to increase "access to healthy and culturally appropriate food" and serve as "a business incubator for local micro-entrepreneurs," including immigrants and refugees who live in the neighborhood.

On paper, this all sounds great.

But just a few blocks outside the gates, informal street vendors – who have long sold goods such as fruit, tamales and ice cream to residents who can't easily access supermarkets – now face heightened harassment. They've become causalities in a citywide crackdown on sidewalk vending spurred by complaints from business owners and residents in more affluent areas.

This isn't just happening in San Diego. The same tensions have been playing out in rapidly gentrifying areas like Los Angeles' Boyle Heights neighborhood, Chicago's Pilsen neighborhood, New York's Queens borough and East Austin, Texas.

In all of these places, because "ethnic," "authentic" and "exotic" foods are seen as cultural assets, they've become magnets for development.

Food vendor at outdoor international marketplace called Fair@44.

Fairat44 via Instagram

A call for food justice

Cities and neighborhoods have long sought to attract educated and affluent residents – people whom sociologist Richard Florida dubbed "the creative class." The thinking goes that these newcomers will spend their dollars and presumably contribute to economic growth and job creation.

Food, it seems, has become the perfect lure.

It's uncontroversial and has broad appeal. It taps into the American Dream and appeals to the multicultural values of many educated, wealthy foodies. Small food businesses, with their relatively low cost of entry, have been a cornerstone of ethnic entrepreneurship in American cities. And initiatives like farmers markets and street fairs don't require much in the way of public investment; instead, they rely on entrepreneurs and community-based organizations to do the heavy lifting.

In City Heights, the Community Development Corporation hosted its first annual City Heights Street Food Festival in 2019 to "get people together around table and food stalls to celebrate another year of community building." Other recent events have included African Restaurant Week, Dia de Los Muertos, New Year Lunar Festival, Soul Food Fest and Brazilian Carnival, all of which rely on food and drink to attract visitors and support local businesses.

Meanwhile, initiatives such as the New Roots Community Farm and the City Heights Farmers' Market have been launched by nonprofits with philanthropic support in the name of "food justice," with the goal of reducing racial disparities in access to healthy food and empowering residents – projects that are particularly appealing to highly educated people who value diversity and democracy.

Upending an existing foodscape

In media coverage of changing foodscapes in low-income neighborhoods like City Heights, you'll rarely find any complaints.

San Diego Magazine's neighborhood guide for City Heights, for example, emphasizes its "claim to authentic international eats, along with live music venues, craft beer, coffee, and outdoor fun." It recommends several ethnic restaurants and warns readers not to be fooled by appearances.

Longtime residents find themselves forced to compete against the "urban food machine"

But that doesn't mean objections don't exist.

Many longtime residents and small-business owners – mostly people of color and immigrants – have, for decades, lived, worked and struggled to feed their families in these neighborhoods. To do so, they've run convenience stores, opened ethnic restaurants, sold food in parks and alleys and created spaces to grow their own food.

All represent strategies to meet community needs in a place mostly ignored by mainstream retailers.

So what happens when new competitors come to town?

Food vendor at outdoor international marketplace called Fair@44.

Fairat44 via Instagram

Starting at a disadvantage

As I document in my book, these ethnic food businesses, because of a lack of financial and technical support, often struggle to compete with new enterprises that feature fresh façades, celebrity chefs, flashy marketing, bogus claims of authenticity and disproportionate media attention. Furthermore, following the arrival of more-affluent residents, existing ones find it increasingly difficult to stay.

My analysis of real estate ads for properties listed in City Heights and other gentrifying San Diego neighborhoods found that access to restaurants, cafés, farmers markets and outdoor dining is a common selling point. The listings I studied from 2019 often enticed potential buyers with lines like "shop at the local farmers' market," "join food truck festivals" and "participate in community food drives!"

San Diego Magazine's home buyer guide for the same year identified City Heights as an "up-and-coming neighborhood," attributing its appeal to its diverse population and eclectic "culinary landscape," including several restaurants and Fair@44.

When I see that City Heights' home prices rose 58% over the past three years, I'm not surprised.

Going up against the urban food machine

Longtime residents find themselves forced to compete against what I call the "urban food machine," a play on sociologist Harvey Molotch's "urban growth machine" – a term he coined more than 50 years ago to explain how cities were being shaped by a loose coalition of powerful elites who sought to profit off urban growth.

I argue that investors and developers use food as a tool for achieving the same ends.

When their work is done, what's left is a rather insipid and tasteless neighborhood, where foodscapes become more of a marketable mishmash of cultures than an ethnic enclave that's evolved organically to meet the needs of residents. The distinctions of time and place start to blur: An "ethnic food district" in San Diego looks no different than one in Chicago or Austin.

Meanwhile, the routines and rhythms of everyday life have changed so much that longtime residents no longer feel like they belong. Their stories and culture reduced to a selling point, they're forced to either recede to the shadows or leave altogether.

It's hard to see how that's a form of inclusion or empowerment.The Conversation


Pascale Joassart-Marcelli is a Professor of Geography and Director, Urban Studies and Food Studies Programs at San Diego State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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