Stansted Airport, which earlier closed after overnight snow, has underlined the scale of the task when inclement weather hits.
The airport's Twitter feed revealed it must clear 1.2 million square metres of paved surfaces and 20kms of airside roads when heavy snow falls.
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The outage struck Hartfield-Jackson Atlanta International Airport at around 1pm local time, stopping all outgoing flights.
It will be a chilly day for many parts with the highest temperatures, about 10 Celsius (50F) in the far northwest.
The social site has been overhauling many of its policies in recent weeks following repeated criticism over how it handles abusive content.