![Smoke from chimneys billows over the rooftops of downtown Prague as temperatures dropped to as low as minus 11 degrees Celsius (12.2 degrees Fahrenheit) in Prague February 4, 2012. REUTERS/David W Cerny ( Smoke from chimneys billows over the rooftops of downtown Prague as temperatures dropped to as low as minus 11 degrees Celsius (12.2 degrees Fahrenheit) in Prague February 4, 2012. REUTERS/David W Cerny (](https://c8.alamy.com/comp/2CXR78G/smoke-from-chimneys-billows-over-the-rooftops-of-downtown-prague-as-temperatures-dropped-to-as-low-as-minus-11-degrees-celsius-122-degrees-fahrenheit-in-prague-february-4-2012-reutersdavid-w-cerny-czech-republic-tags-cityscape-environment-2CXR78G.jpg)
Smoke from chimneys billows over the rooftops of downtown Prague as temperatures dropped to as low as minus 11 degrees Celsius (12.2 degrees Fahrenheit) in Prague February 4, 2012. REUTERS/David W Cerny (
![A wave splashes onto a wall on a windy winter day in Grandson, near Yverdon February 4, 2012. Temperatures dropped to as low as minus 11 degrees Celsius (12.2 degrees Fahrenheit) in A wave splashes onto a wall on a windy winter day in Grandson, near Yverdon February 4, 2012. Temperatures dropped to as low as minus 11 degrees Celsius (12.2 degrees Fahrenheit) in](https://c8.alamy.com/comp/2CY3FMJ/a-wave-splashes-onto-a-wall-on-a-windy-winter-day-in-grandson-near-yverdon-february-4-2012-temperatures-dropped-to-as-low-as-minus-11-degrees-celsius-122-degrees-fahrenheit-in-switzerland-and-other-parts-of-europe-reutersdenis-balibouse-switzerland-tags-environment-2CY3FMJ.jpg)
A wave splashes onto a wall on a windy winter day in Grandson, near Yverdon February 4, 2012. Temperatures dropped to as low as minus 11 degrees Celsius (12.2 degrees Fahrenheit) in
![Smoke from chimneys billows over the rooftops of downtown Prague as temperatures dropped to as low as minus 11 degrees Celsius (12.2 degrees Fahrenheit), Czech Republic, January 7, 2017. REUTERS/David W Cerny Smoke from chimneys billows over the rooftops of downtown Prague as temperatures dropped to as low as minus 11 degrees Celsius (12.2 degrees Fahrenheit), Czech Republic, January 7, 2017. REUTERS/David W Cerny](https://c8.alamy.com/comp/2CJ3CFY/smoke-from-chimneys-billows-over-the-rooftops-of-downtown-prague-as-temperatures-dropped-to-as-low-as-minus-11-degrees-celsius-122-degrees-fahrenheit-czech-republic-january-7-2017-reutersdavid-w-cerny-2CJ3CFY.jpg)