The science behind Europe’s Siberian chill this week

Nice out. The A48 in the snow. Image: Getty.

The so-called “Beast from the East” arrived in the UK this week, bringing unusually cold weather – about 7°C colder than the historical average for this time of year. Wind chill is making temperatures feel particularly arctic.

So how did the Siberian gusts come to arrive on Europe’s doorstep?

The movement of air across the globe, and the weather it brings with it, is governed by three major influences: gravity, the sun, and something called the Coriolis effect. The influence of gravity is simple, constantly pulling air towards the Earth’s surface.

The rise and fall of the sun dictates whether the air stays there. During the day, radiation from the sun heats the Earth, warming air directly above the surface and causing it to rise, leaving behind a region of low pressure (a low density of air particles). As the air rises, it cools and spreads outwards.

This mass of air, now denser than the air below it, sinks back down under the force of gravity, and naturally flows back towards the lower pressure region of air, creating a cycle of air circulation. These circulating patterns of wind exist on an intercontinental scale, transporting heat all the way from the tropics to the poles.

However, thanks to the Coriolis effect – the deflection of objects moving in a straight path due to the Earth’s rotation – the winds do not travel directly north or south. To illustrate this effect, imagine a spinning top. Parts of the spinning top closer to the spindle rotate at slower speeds than parts further away, as they have less distance to travel to complete a full circle. Similarly, the equator has to travel much faster than the poles do as the Earth rotates. As air travels north from the equator, its extra momentum compared to the slower rotating land that it is moving over makes it curve across to the east, while air travelling to the south pole curves westward.

In the northern hemisphere, this interaction between the Coriolis effect and the circulation systems produces the northern polar jet stream: high altitude currents of air blowing eastwards at hundreds of miles per hour, moving weather systems around the globe. This causes the UK’s prevailing westerly and south-westerly winds, which usually draw weather systems in from the relatively warm Atlantic and shield us from colder air masses to the east.

The shape of the jet streams is not rigid – it follows a meandering path, much like a slithering snake. Occasionally, the jet stream path can become so twisted that it folds back upon itself, reversing the direction of the prevailing wind, and drawing in cold air from the east.


This is exactly what just happened. In the last couple of days, the bitterly cold front combined with water vapour in the air to carpet the country in a blanket of brilliant white.

As the warmth of the sun disappears each night, the cold can feel all the more biting. But in the absence of the sun’s heat, the smaller difference in temperature between air near the ground and higher up makes air circulate more slowly. This often creates calmer conditions that might just provide a brief respite from the extra chill of the wind. For this same reason, air passengers generally experience smoother flying conditions when flying at night.

If you live in the city however, your experience of the “beast” can vary wildly from place to place. Cities continue to produce heat at night, generating their own microclimates. This man-made heat keeps air moving, and warms city dwellers up more than those in rural areas. At the same time, the ordered formation of buildings in cities creates strong wind corridors that are certainly best avoided at times like these.

Wherever you are experiencing this freezing weather, you can at least be thankful that you are here on Earth. Wind circulation patterns on other planets produce far more extreme weather than we will ever experience. Visitors to Venus, for example, would experience some serious turbulence when approaching landing, as the 500°C difference between surface and cloud generates extreme air circulation.

The ConversationHowever, if you were lucky enough to touch down and survive the experience of the crushing pressure found on Venus’ surface, you would feel nothing more than a gentle breeze, thanks to the planet’s very slow rotation, weak Coriolis effect, and dense air. You might want to seek shelter though – at close to 460°C, suddenly a cold chill doesn’t seem so bad.

Gareth Dorrian, Post Doctoral Research Associate in Space Science, Nottingham Trent University and Ian Whittaker, Lecturer, Nottingham Trent University.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

High streets and shopping malls face a ‘domino effect’ from major store closures

Another one bites the dust: House of Fraser plans to close the majority of its stores. Image: Getty.

Traditional retail is in the centre of a storm – and British department store chain House of Fraser is the latest to succumb to the tempest. The company plans to close 31 of its 59 shops – including its flagship store in Oxford Street, London – by the beginning of 2019. The closures come as part of a company voluntary arrangement, which is an insolvency deal designed to keep the chain running while it renegotiates terms with landlords. The deal will be voted on by creditors within the month.

Meanwhile in the US, the world’s largest retail market, Sears has just announced that it will be closing more than 70 of its stores in the near future.

This trend of major retailers closing multiple outlets exists in several Western countries – and its magnitude seems to be unrelated to the fundamentals of the economy. The US, for example, has recently experienced a clear decoupling of store closures from overall economic growth. While the US economy grew a healthy 2.3 per cent in 2017, the year ended with a record number of store closings, nearly 9,000 while 50 major chains filed for bankruptcy.

Most analysts and industry experts agree that this is largely due to the growth of e-commerce – and this is not expected to diminish anytime soon. A further 12,000 stores are expected to close in the US before the end of 2018. Similar trends are being seen in markets such as the UK and Canada.

Pushing down profits

Perhaps the most obvious impact of store closures is on the revenues and profitability of established brick-and-mortar retailers, with bankruptcies in the US up by nearly a third in 2017. The cost to investors in the retail sector has been severe – stocks of firms such as Sears have lost upwards of 90 per cent of their market value in the last ten years. By contrast, Amazon’s stock price is up over 2,000 per cent in the same period – more than 49,000 per cent when considering the last 20 years. This is a trend that the market does not expect to change, as the ratio of price to earnings for Amazon stands at ten times that of the best brick-and-mortar retailers.

Although unemployment levels reached a 17-year low in 2017, the retail sector in the US shed a net 66,500 jobs. Landlords are losing longstanding tenants. The expectation is that roughly 25 per cent of shopping malls in the US are at high risk of closing one of their anchor tenants such as a Macy’s, which could set off a series of store closures and challenge the very viability of the mall. One out of every five malls is expected to close by 2022 – a prospect which has put downward pressure on retail real estate prices and on the finances of the firms that own and manage these venues.

In the UK, high streets are struggling through similar issues. And given that high streets have historically been the heart of any UK town or city, there appears to be a fundamental need for businesses and local councils to adapt to the radical changes affecting the retail sector to preserve their high streets’ vitality and financial viability.


The costs to society

While attention is focused on the direct impacts on company finances, employment and landlord rents, store closures can set off a “domino effect” on local governments and businesses, which come at a significant cost to society. For instance, closures can have a knock-on effect for nearby businesses – when large stores close, the foot traffic to neighbouring establishments is also reduced, which endangers the viability of other local businesses. For instance, Starbucks has recently announced plans to close all its 379 Teavana stores. Primarily located inside shopping malls, they have harshly suffered from declining mall traffic in recent years.

Store closures can also spell trouble for local authorities. When retailers and neighbouring businesses close, they reduce the taxable revenue base that many municipalities depend on in order to fund local services. Add to this the reduction in property taxes stemming from bankrupt landlords and the effect on municipal funding can be substantial. Unfortunately, until e-commerce tax laws are adapted, municipalities will continue to face financial challenges as more and more stores close.

It’s not just local councils, but local development which suffers when stores close. For decades, many cities in the US and the UK, for exmaple Detroit and Liverpool, have heavily invested in efforts to rejuvenate their urban cores after years of decay in the 1970s and 1980s. Bringing shops, bars and other businesses back to once derelict areas has been key to this redevelopment. But today, with businesses closing, cities could once again face the prospect of seeing their efforts unravel as their key urban areas become less attractive and populations move elsewhere.

Commercial ecosystems featuring everything from large chain stores to small independent businesses are fragile and sensitive to change. When a store closes it doesn’t just affect employees or shareholders – it can have widespread and lasting impacts on the local community, and beyond. Controlling this “domino effect” is going to be a major challenge for local governments and businesses for years to come.

Omar Toulan, Professor in Strategy and International Management, IMD Business School and Niccolò Pisani, Assistant Professor of International Management, University of Amsterdam.

This article was originally published on The Conversation. Read the original article.